Get asynchronous thread dump (jstack)

# Conflicts:
#	CHANGELOG.md
#	src/allocTracer.cpp
#	src/allocTracer.h

.gitignore

@@ -1,5 +1,6 @@
 /build/
 /nbproject/
+/out/
 /.idea/
 /test/*.class
 .vscode

CHANGELOG.md

@@ -1,6 +1,98 @@
 # Changelog
 
-## [1.6] 2019-09-09
+## [2.0-b1] - Early access
+
+### Features
+ - Profile multiple events together (cpu + alloc + lock)
+ - HTML 5 Flame Graphs: faster rendering, smaller size
+ - JFR v2 output format, compatible with FlightRecorder API
+ - Automatically turn profiling on/off at `--begin`/`--end` functions
+ - Time-to-safepoint profiling
+
+### Improvements
+ - Unlimited frame buffer. Removed `-b` option and 64K stack traces limit
+ - Record CPU load in JFR format
+
+### Changes
+ - Removed non-ASL code. No more CDDL license
+
+## [1.8.3] - 2021-01-06
+
+### Improvements
+ - libasyncProfiler.dylib symlink on macOS
+
+### Bug fixes
+ - Fixed possible deadlock on non-HotSpot JVMs
+ - Gracefully stop profiler when terminating JVM
+ - Fixed GetStackTrace problem after RedefineClasses
+
+## [1.8.2] - 2020-11-02
+
+### Improvements
+ - AArch64 build is now provided out of the box
+ - Compatibility with JDK 15 and JDK 16
+
+### Bug fixes
+ - More careful native stack walking in wall-clock mode
+ - `resume` command is not compatible with JFR format
+ - Wrong allocation sizes on JDK 8u262
+
+## [1.8.1] - 2020-09-05
+
+### Improvements
+ - Possibility to specify application name instead of `pid` (contributed by @yuzawa-san)
+
+### Bug fixes
+ - Fixed long attach time and slow class loading on JDK 8
+ - `UnsatisfiedLinkError` during Java method profiling
+ - Avoid reading `/proc/kallsyms` when `--all-user` is specified
+
+## [1.8] - 2020-08-10
+
+### Features
+ - Converters between different output formats:
+   - JFR -> nflx (FlameScope)
+   - Collapsed stacks -> HTML 5 Flame Graph 
+
+### Improvements
+ - `profiler.sh` no longer requires bash (contributed by @cfstras)
+ - Fixed long attach time and slow class loading on JDK 8
+ - Fixed deadlocks in wall-clock profiling mode
+ - Per-thread reverse Flame Graph and Call Tree
+ - ARM build now works with ARM and THUMB flavors of JDK
+
+### Changes
+ - Release package is extracted into a separate folder
+
+## [1.7.1] - 2020-05-14
+
+### Features
+ - LBR call stack support (available since Haswell)
+
+### Improvements
+ - `--filter` to profile only specified thread IDs in wall-clock mode
+ - `--safe-mode` to disable selected stack recovery techniques
+
+## [1.7] - 2020-03-17
+
+### Features
+ - Profile invocations of arbitrary Java methods
+ - Filter stack traces by the given name pattern
+ - Java API to filter monitored threads
+ - `--cstack`/`--no-cstack` option
+
+### Improvements
+ - Thread names and Java thread IDs in JFR output
+ - Wall clock profiler distinguishes RUNNABLE vs. SLEEPING threads
+ - Stable profiling interval in wall clock mode
+ - C++ function names as events, e.g. `-e VMThread::execute`
+ - `check` command to test event availability
+ - Allow shading of AsyncProfiler API
+ - Enable CPU profiling on WSL
+ - Enable allocation profiling on Zing
+ - Reduce the amount of `unknown_Java` samples
+
+## [1.6] - 2019-09-09
 
 ### Features
  - Pause/resume profiling

Makefile

@@ -1,59 +1,105 @@
-PROFILER_VERSION=1.6
+PROFILER_VERSION=2.0-b1
 JATTACH_VERSION=1.5
-LIB_PROFILER=libasyncProfiler.so
+JAVAC_RELEASE_VERSION=6
+
+PACKAGE_NAME=async-profiler-$(PROFILER_VERSION)-$(OS_TAG)-$(ARCH_TAG)
+PACKAGE_DIR=/tmp/$(PACKAGE_NAME)
+
+LIB_PROFILER=libasyncProfiler.$(SOEXT)
+LIB_PROFILER_SO=libasyncProfiler.so
 JATTACH=jattach
-PROFILER_JAR=async-profiler.jar
-CC=gcc
-CFLAGS=-O2
-CPP=g++
-CPPFLAGS=-O2
+API_JAR=async-profiler.jar
+CONVERTER_JAR=converter.jar
+
+CFLAGS=-O3 -fno-omit-frame-pointer -fvisibility=hidden
+CXXFLAGS=-O3 -fno-omit-frame-pointer -fvisibility=hidden
 INCLUDES=-I$(JAVA_HOME)/include
 LIBS=-ldl -lpthread
+
 JAVAC=$(JAVA_HOME)/bin/javac
 JAR=$(JAVA_HOME)/bin/jar
 
+SOURCES := $(wildcard src/*.cpp)
+HEADERS := $(wildcard src/*.h)
+API_SOURCES := $(wildcard src/api/one/profiler/*.java)
+CONVERTER_SOURCES := $(shell find src/converter -name '*.java')
+
 ifeq ($(JAVA_HOME),)
   export JAVA_HOME:=$(shell java -cp . JavaHome)
 endif
 
 OS:=$(shell uname -s)
 ifeq ($(OS), Darwin)
-  CPPFLAGS += -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE
+  CXXFLAGS += -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE
   INCLUDES += -I$(JAVA_HOME)/include/darwin
-  RELEASE_TAG:=$(PROFILER_VERSION)-macos-x64
+  SOEXT=dylib
+  OS_TAG=macos
 else
   LIBS += -lrt
   INCLUDES += -I$(JAVA_HOME)/include/linux
-  RELEASE_TAG:=$(PROFILER_VERSION)-linux-x64
+  SOEXT=so
+  ifeq ($(findstring musl,$(shell ldd /bin/ls)),musl)
+    OS_TAG=linux-musl
+  else
+    OS_TAG=linux
+  endif
+endif
+
+ARCH:=$(shell uname -m)
+ifeq ($(ARCH),x86_64)
+  ARCH_TAG=x64
+else
+  ifeq ($(findstring arm,$(ARCH)),arm)
+    ARCH_TAG=arm
+  else
+    ifeq ($(findstring aarch64,$(ARCH)),aarch64)
+      ARCH_TAG=aarch64
+    else
+      ARCH_TAG=x86
+    endif
+  endif
 endif
 
 
 .PHONY: all release test clean
 
-all: build build/$(LIB_PROFILER) build/$(JATTACH) build/$(PROFILER_JAR)
+all: build build/$(LIB_PROFILER) build/$(JATTACH) build/$(API_JAR) build/$(CONVERTER_JAR)
 
-release: build async-profiler-$(RELEASE_TAG).tar.gz
+release: build $(PACKAGE_NAME).tar.gz
 
-async-profiler-$(RELEASE_TAG).tar.gz: build/$(LIB_PROFILER) build/$(JATTACH) \
-                                      build/$(PROFILER_JAR) profiler.sh LICENSE *.md
-	chmod 755 build profiler.sh
-	chmod 644 LICENSE *.md
-	tar cvzf $@ $^
+$(PACKAGE_NAME).tar.gz: build/$(LIB_PROFILER) build/$(JATTACH) \
+                        build/$(API_JAR) build/$(CONVERTER_JAR) \
+                        profiler.sh LICENSE *.md
+	mkdir -p $(PACKAGE_DIR)
+	cp -RP build profiler.sh LICENSE *.md $(PACKAGE_DIR)
+	chmod -R 755 $(PACKAGE_DIR)
+	chmod 644 $(PACKAGE_DIR)/LICENSE $(PACKAGE_DIR)/*.md $(PACKAGE_DIR)/build/*.jar
+	tar cvzf $@ -C $(PACKAGE_DIR)/.. $(PACKAGE_NAME)
+	rm -r $(PACKAGE_DIR)
+
+%.$(SOEXT): %.so
+	-ln -s $(<F) $@
 
 build:
 	mkdir -p build
 
-build/$(LIB_PROFILER): src/*.cpp src/*.h
-	$(CPP) $(CPPFLAGS) -DPROFILER_VERSION=\"$(PROFILER_VERSION)\" $(INCLUDES) -fPIC -shared -o $@ src/*.cpp $(LIBS)
+build/$(LIB_PROFILER_SO): $(SOURCES) $(HEADERS)
+	$(CXX) $(CXXFLAGS) -DPROFILER_VERSION=\"$(PROFILER_VERSION)\" $(INCLUDES) -fPIC -shared -o $@ $(SOURCES) $(LIBS)
 
 build/$(JATTACH): src/jattach/jattach.c
 	$(CC) $(CFLAGS) -DJATTACH_VERSION=\"$(JATTACH_VERSION)\" -o $@ $^
 
-build/$(PROFILER_JAR): src/java/one/profiler/*.java
-	mkdir -p build/classes
-	$(JAVAC) -source 6 -target 6 -d build/classes $^
-	$(JAR) cvf $@ -C build/classes .
-	rm -rf build/classes
+build/$(API_JAR): $(API_SOURCES)
+	mkdir -p build/api
+	$(JAVAC) -source $(JAVAC_RELEASE_VERSION) -target $(JAVAC_RELEASE_VERSION) -d build/api $^
+	$(JAR) cvf $@ -C build/api .
+	$(RM) -r build/api
+
+build/$(CONVERTER_JAR): $(CONVERTER_SOURCES) src/converter/MANIFEST.MF
+	mkdir -p build/converter
+	$(JAVAC) -source 7 -target 7 -d build/converter $(CONVERTER_SOURCES)
+	$(JAR) cvfm $@ src/converter/MANIFEST.MF -C build/converter .
+	$(RM) -r build/converter
 
 test: all
 	test/smoke-test.sh
@@ -63,4 +109,4 @@ test: all
 	echo "All tests passed"
 
 clean:
-	rm -rf build
+	$(RM) -r build

README.md

@@ -1,25 +1,38 @@
 # async-profiler
 
+[![Build Status](https://travis-ci.org/jvm-profiling-tools/async-profiler.svg?branch=master)](https://travis-ci.org/jvm-profiling-tools/async-profiler)
+
 This project is a low overhead sampling profiler for Java
 that does not suffer from [Safepoint bias problem](http://psy-lob-saw.blogspot.ru/2016/02/why-most-sampling-java-profilers-are.html).
 It features HotSpot-specific APIs to collect stack traces
 and to track memory allocations. The profiler works with
-OpenJDK, Oracle JDK and other Java runtimes based on HotSpot JVM.
+OpenJDK, Oracle JDK and other Java runtimes based on the HotSpot JVM.
 
 async-profiler can trace the following kinds of events:
  - CPU cycles
  - Hardware and Software performance counters like cache misses, branch misses, page faults, context switches etc.
  - Allocations in Java Heap
  - Contented lock attempts, including both Java object monitors and ReentrantLocks
+ 
+## Usage
+
+See our [Wiki](https://github.com/jvm-profiling-tools/async-profiler/wiki) or [3 hours playlist](https://www.youtube.com/playlist?list=PLNCLTEx3B8h4Yo_WvKWdLvI9mj1XpTKBr) to learn about all set of features. 
 
 ## Download
 
-Latest release (1.6):
+Latest release (1.8.3):
 
- - Linux x64 (glibc): [async-profiler-1.6-linux-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.6/async-profiler-1.6-linux-x64.tar.gz)
- - Linux x64 (musl): [async-profiler-1.6-linux-x64-musl.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.6/async-profiler-1.6-linux-x64-musl.tar.gz)
- - Linux ARM: [async-profiler-1.6-linux-arm.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.6/async-profiler-1.6-linux-arm.tar.gz)
- - macOS x64: [async-profiler-1.6-macos-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.6/async-profiler-1.6-macos-x64.tar.gz)
+ - Linux x64 (glibc): [async-profiler-1.8.3-linux-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.3/async-profiler-1.8.3-linux-x64.tar.gz)
+ - Linux x86 (glibc): [async-profiler-1.8.3-linux-x86.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.3/async-profiler-1.8.3-linux-x86.tar.gz)
+ - Linux x64 (musl): [async-profiler-1.8.3-linux-musl-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.3/async-profiler-1.8.3-linux-musl-x64.tar.gz)
+ - Linux ARM: [async-profiler-1.8.3-linux-arm.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.3/async-profiler-1.8.3-linux-arm.tar.gz)
+ - Linux AArch64: [async-profiler-1.8.3-linux-aarch64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.3/async-profiler-1.8.3-linux-aarch64.tar.gz)
+ - macOS x64: [async-profiler-1.8.3-macos-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.3/async-profiler-1.8.3-macos-x64.tar.gz)
+
+[Early access](https://github.com/jvm-profiling-tools/async-profiler/releases/tag/v2.0-b1) (2.0-b1):
+
+ - Linux x64 (glibc): [async-profiler-2.0-b1-linux-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v2.0-b1/async-profiler-2.0-b1-linux-x64.tar.gz)
+ - macOS x64: [async-profiler-2.0-b1-macos-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v2.0-b1/async-profiler-2.0-b1-macos-x64.tar.gz)
 
 [Previous releases](https://github.com/jvm-profiling-tools/async-profiler/releases)
 
@@ -30,448 +43,11 @@ Latest release (1.6):
 
 Note: macOS profiling is limited to user space code only.
 
-## CPU profiling
-
-In this mode profiler collects stack trace samples that include **Java** methods,
-**native** calls, **JVM** code and **kernel** functions.
-
-The general approach is receiving call stacks generated by `perf_events`
-and matching them up with call stacks generated by `AsyncGetCallTrace`,
-in order to produce an accurate profile of both Java and native code.
-Additionally, async-profiler provides a workaround to recover stack traces
-in some [corner cases](https://bugs.openjdk.java.net/browse/JDK-8178287)
-where `AsyncGetCallTrace` fails.
-
-This approach has the following advantages compared to using `perf_events`
-directly with a Java agent that translates addresses to Java method names:
-
-* Works on older Java versions because it doesn't require
-`-XX:+PreserveFramePointer`, which is only available in JDK 8u60 and later.
-
-* Does not introduce the performance overhead from `-XX:+PreserveFramePointer`,
-which can in rare cases be as high as 10%.
-
-* Does not require generating a map file to map Java code addresses to method
-names.
-
-* Works with interpreter frames.
-
-* Does not require writing out a perf.data file for further processing in
-user space scripts.
-
-## ALLOCATION profiling
-
-Instead of detecting CPU-consuming code, the profiler can be configured
-to collect call sites where the largest amount of heap memory is allocated.
-
-async-profiler does not use intrusive techniques like bytecode instrumentation
-or expensive DTrace probes which have significant performance impact.
-It also does not affect Escape Analysis or prevent from JIT optimizations
-like allocation elimination. Only actual heap allocations are measured.
-
-The profiler features TLAB-driven sampling. It relies on HotSpot-specific
-callbacks to receive two kinds of notifications:
- - when an object is allocated in a newly created TLAB;
- - when an object is allocated on a slow path outside TLAB.
-
-This means not each allocation is counted, but only allocations every _N_ kB,
-where _N_ is the average size of TLAB. This makes heap sampling very cheap
-and suitable for production. On the other hand, the collected data
-may be incomplete, though in practice it will often reflect the top allocation
-sources.
-
-Sampling interval can be adjusted with `-i` option.
-For example, `-i 500k` will take one sample after 500 KB of allocated
-space on average. However, intervals less than TLAB size will not take effect.
-If you want to profile allocations with higher frequency, reduce the TLAB size,
-e.g.
-```
--XX:MinTLABSize=1 -XX:TLABSize=1 -XX:-ResizeTLAB
-```
-
-Unlike Java Mission Control which uses similar approach, async-profiler
-does not require Java Flight Recorder or any other JDK commercial feature.
-It is completely based on open source technologies and it works with OpenJDK.
-
-The minimum supported JDK version is 7u40 where the TLAB callbacks appeared.
-
-Heap profiler requires HotSpot debug symbols. Oracle JDK already has them
-embedded in `libjvm.so`, but in OpenJDK builds they are typically shipped
-in a separate package. For example, to install OpenJDK debug symbols on
-Debian / Ubuntu, run:
-```
-# apt install openjdk-8-dbg
-```
-or for OpenJDK 11:
-```
-# apt install openjdk-11-dbg
-```
-
-On Gentoo the `icedtea` OpenJDK package can be built with the per-package setting
-`FEATURES="nostrip"` to retain symbols.
-
-### Wall-clock profiling
-
-`-e wall` option tells async-profiler to sample all threads equally every given
-period of time regardless of thread status: Running, Sleeping or Blocked.
-For instance, this can be helpful when profiling application start-up time.
-
-Wall-clock profiler is most useful in per-thread mode: `-t`.
-
-Example: `./profiler.sh -e wall -t -i 5ms -f result.svg 8983`
-
 ## Building
 
-Build status: [![Build Status](https://travis-ci.org/jvm-profiling-tools/async-profiler.svg?branch=master)](https://travis-ci.org/jvm-profiling-tools/async-profiler)
-
 Make sure the `JAVA_HOME` environment variable points to your JDK installation,
 and then run `make`. GCC is required. After building, the profiler agent binary
 will be in the `build` subdirectory. Additionally, a small application `jattach`
 that can load the agent into the target process will also be compiled to the
 `build` subdirectory.
 
-## Basic Usage
-
-As of Linux 4.6, capturing kernel call stacks using `perf_events` from a non-
-root process requires setting two runtime variables. You can set them using
-sysctl or as follows:
-
-```
-# echo 1 > /proc/sys/kernel/perf_event_paranoid
-# echo 0 > /proc/sys/kernel/kptr_restrict
-```
-
-To run the agent and pass commands to it, the helper script `profiler.sh`
-is provided. A typical workflow would be to launch your Java application,
-attach the agent and start profiling, exercise your performance scenario, and
-then stop profiling. The agent's output, including the profiling results, will
-be displayed in the Java application's standard output.
-
-Example:
-
-```
-$ jps
-9234 Jps
-8983 Computey
-$ ./profiler.sh start 8983
-$ ./profiler.sh stop 8983
-```
-
-Alternatively, you may specify `-d` (duration) argument to profile
-the application for a fixed period of time with a single command.
-
-```
-$ ./profiler.sh -d 30 8983
-```
-
-By default, the profiling frequency is 100Hz (every 10ms of CPU time).
-Here is a sample of the output printed to the Java application's terminal:
-
-```
---- Execution profile ---
-Total samples:           687
-Unknown (native):        1 (0.15%)
-
---- 6790000000 (98.84%) ns, 679 samples
-  [ 0] Primes.isPrime
-  [ 1] Primes.primesThread
-  [ 2] Primes.access$000
-  [ 3] Primes$1.run
-  [ 4] java.lang.Thread.run
-
-... a lot of output omitted for brevity ...
-
-          ns  percent  samples  top
-  ----------  -------  -------  ---
-  6790000000   98.84%      679  Primes.isPrime
-    40000000    0.58%        4  __do_softirq
-
-... more output omitted ...
-```
-
-This indicates that the hottest method was `Primes.isPrime`, and the hottest
-call stack leading to it comes from `Primes.primesThread`.
-
-## Launching as an Agent
-
-If you need to profile some code as soon as the JVM starts up, instead of using the `profiler.sh` script,
-it is possible to attach async-profiler as an agent on the command line. For example:
-
-```
-$ java -agentpath:/path/to/libasyncProfiler.so=start,file=profile.svg ...
-```
-
-Agent library is configured through the JVMTI argument interface.
-The format of the arguments string is described
-[in the source code](https://github.com/jvm-profiling-tools/async-profiler/blob/b7e9e6b955210784d5dc1d1839bb0febab1b712b/src/arguments.cpp#L34).
-The `profiler.sh` script actually converts command line arguments to the that format.
-
-For instance, `-e alloc` is converted to `event=alloc`, `-f profile.svg`
-is converted to `file=profile.svg` and so on. But some arguments are processed
-directly by `profiler.sh` script. E.g. `-d 5` results in 3 actions:
-attaching profiler agent with start command, sleeping for 5 seconds,
-and then attaching the agent again with stop command.
-
-## Flame Graph visualization
-
-async-profiler provides out-of-the-box [Flame Graph](https://github.com/BrendanGregg/FlameGraph) support.
-Specify `-o svg` argument to dump profiling results as an interactive SVG
-immediately viewable in all mainstream browsers.
-Also, SVG output format will be chosen automatically if the target
-filename ends with `.svg`.
-
-```
-$ jps
-9234 Jps
-8983 Computey
-$ ./profiler.sh -d 30 -f /tmp/flamegraph.svg 8983
-```
-
-![Example](https://github.com/jvm-profiling-tools/async-profiler/blob/master/demo/SwingSet2.svg)
-
-## Profiler Options
-
-The following is a complete list of the command-line options accepted by
-`profiler.sh` script.
-
-* `start` - starts profiling in semi-automatic mode, i.e. profiler will run
-until `stop` command is explicitly called.
-
-* `resume` - starts or resumes earlier profiling session that has been stopped.
-All the collected data remains valid. The profiling options are not preserved
-between sessions, and should be specified again.
-
-* `stop` - stops profiling and prints the report.
-
-* `status` - prints profiling status: whether profiler is active and
-for how long.
-
-* `list` - show the list of available profiling events. This option still
-requires PID, since supported events may differ depending on JVM version.
-
-* `-d N` - the profiling duration, in seconds. If no `start`, `resume`, `stop`
-or `status` option is given, the profiler will run for the specified period
-of time and then automatically stop.  
-Example: `./profiler.sh -d 30 8983`
-
-* `-e event` - the profiling event: `cpu`, `alloc`, `lock`, `cache-misses` etc.
-Use `list` to see the complete list of available events.
-
-  In allocation profiling mode the top frame of every call trace is the class
-of the allocated object, and the counter is the heap pressure (the total size
-of allocated TLABs or objects outside TLAB).
-
-  In lock profiling mode the top frame is the class of lock/monitor, and
-the counter is number of nanoseconds it took to enter this lock/monitor.  
-
-  Two special event types are supported on Linux: hardware breakpoints
-and kernel tracepoints:
-  - `-e mem:<func>[:rwx]` sets read/write/exec breakpoint at function
-  `<func>`. The format of `mem` event is the same as in `perf-record`.
-  Execution breakpoints can be also specified by the function name,
-  e.g. `-e malloc` will trace all calls of native `malloc` function.
-  - `-e trace:<id>` sets a kernel tracepoint. It is possible to specify
-  tracepoint symbolic name, e.g. `-e syscalls:sys_enter_open` will trace
-  all `open` syscalls.
-
-* `-i N` - sets the profiling interval in nanoseconds or in other units,
-if N is followed by `ms` (for milliseconds), `us` (for microseconds)
-or `s` (for seconds). Only CPU active time is counted. No samples
-are collected while CPU is idle. The default is 10000000 (10ms).  
-Example: `./profiler.sh -i 500us 8983`
-
-* `-j N` - sets the Java stack profiling depth. This option will be ignored if N is greater 
-than default 2048.  
-Example: `./profiler.sh -j 30 8983`
-
-* `-b N` - sets the frame buffer size, in the number of Java
-method ids that should fit in the buffer. If you receive messages about an
-insufficient frame buffer size, increase this value from the default.  
-Example: `./profiler.sh -b 5000000 8983`
-
-* `-t` - profile threads separately. Each stack trace will end with a frame
-that denotes a single thread.  
-Example: `./profiler.sh -t 8983`
-
-* `-s` - print simple class names instead of FQN.
-
-* `-g` - print method signatures.
-
-* `-a` - annotate Java method names by adding `_[j]` suffix.
-
-* `-o fmt` - specifies what information to dump when profiling ends.
-`fmt` can be one of the following options:
-  - `summary` - dump basic profiling statistics;
-  - `traces[=N]` - dump call traces (at most N samples);
-  - `flat[=N]` - dump flat profile (top N hot methods);
-  - `jfr` - dump events in Java Flight Recorder format readable by Java Mission Control.
-  This *does not* require JDK commercial features to be enabled.
-  - `collapsed[=C]` - dump collapsed call traces in the format used by
-  [FlameGraph](https://github.com/brendangregg/FlameGraph) script. This is
-  a collection of call stacks, where each line is a semicolon separated list
-  of frames followed by a counter.
-  - `svg[=C]` - produce Flame Graph in SVG format.
-  - `tree[=C]` - produce call tree in HTML format.  
-     --reverse option will generate backtrace view. 
-  
-  `C` is a counter type:
-  - `samples` - the counter is a number of samples for the given trace;
-  - `total` - the counter is a total value of collected metric, e.g. total allocation size.
-  
-  `summary`, `traces` and `flat` can be combined together.  
-  The default format is `summary,traces=200,flat=200`.
-
-* `--title TITLE`, `--width PX`, `--height PX`, `--minwidth PX`, `--reverse` - FlameGraph parameters.  
-Example: `./profiler.sh -f profile.svg --title "Sample CPU profile" --minwidth 0.5 8983`
-
-* `-f FILENAME` - the file name to dump the profile information to.  
-Example: `./profiler.sh -o collapsed -f /tmp/traces.txt 8983`
-
-* `--all-user` - include only user-mode events. This option is helpful when kernel profiling
-is restricted by `perf_event_paranoid` settings.  
-`--all-kernel` is its counterpart option for including only kernel-mode events.
-
-* `-v`, `--version` - prints the version of profiler library. If PID is specified,
-gets the version of the library loaded into the given process.
-
-## Profiling Java in a container
-
-It is possible to profile Java processes running in a Docker or LXC container
-both from within a container and from the host system.
-
-When profiling from the host, `pid` should be the Java process ID in the host
-namespace. Use `ps aux | grep java` or `docker top <container>` to find
-the process ID.
-
-async-profiler should be run from the host by a privileged user - it will
-automatically switch to the proper pid/mount namespace and change
-user credentials to match the target process. Also make sure that
-the target container can access `libasyncProfiler.so` by the same
-absolute path as on the host.
-
-By default, Docker container restricts the access to `perf_event_open`
-syscall. So, in order to allow profiling inside a container, you'll need
-to modify [seccomp profile](https://docs.docker.com/engine/security/seccomp/)
-or disable it altogether with `--security-opt=seccomp:unconfined` option.
-
-Alternatively, if changing Docker configuration is not possible,
-you may fall back to `-e itimer` profiling mode, see [Troubleshooting](#troubleshooting).
-
-## Restrictions/Limitations
-
-* On most Linux systems, `perf_events` captures call stacks with a maximum depth
-of 127 frames. On recent Linux kernels, this can be configured using
-`sysctl kernel.perf_event_max_stack` or by writing to the
-`/proc/sys/kernel/perf_event_max_stack` file.
-
-* Profiler allocates 8kB perf_event buffer for each thread of the target process.
-Make sure `/proc/sys/kernel/perf_event_mlock_kb` value is large enough
-(more than `8 * threads`) when running under unprivileged user.
-Otherwise the message _"perf_event mmap failed: Operation not permitted"_
-will be printed, and no native stack traces will be collected.
-
-* There is no bullet-proof guarantee that the `perf_events` overflow signal
-is delivered to the Java thread in a way that guarantees no other code has run,
-which means that in some rare cases, the captured Java stack might not match
-the captured native (user+kernel) stack.
-
-*  You will not see the non-Java frames _preceding_ the Java frames on the
-stack. For example, if `start_thread` called `JavaMain` and then your Java
-code started running, you will not see the first two frames in the resulting
-stack. On the other hand, you _will_ see non-Java frames (user and kernel)
-invoked by your Java code.
-
-* No Java stacks will be collected if `-XX:MaxJavaStackTraceDepth` is zero
-or negative.
-
-* Too short profiling interval may cause continuous interruption of heavy
-system calls like `clone()`, so that it will never complete;
-see [#97](https://github.com/jvm-profiling-tools/async-profiler/issues/97).
-The workaround is simply to increase the interval.
-
-* When agent is not loaded at JVM startup (by using -agentpath option) it is
-highly recommended to use `-XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints` JVM flags.
-Without those flags the profiler will still work correctly but results might be
-less accurate e.g. without `-XX:+DebugNonSafepoints` there is a high chance that simple inlined methods will not appear in the profile. When agent is attached at runtime `CompiledMethodLoad` JVMTI event
-enables debug info, but only for methods compiled after the event is turned on.
-
-## Troubleshooting
-
-```
-Failed to change credentials to match the target process: Operation not permitted
-```
-Due to limitation of HotSpot Dynamic Attach mechanism, the profiler must be run
-by exactly the same user (and group) as the owner of target JVM process.
-If profiler is run by a different user, it will try to automatically change
-current user and group. This will likely succeed for `root`, but not for
-other users, resulting in the above error.
-
-```
-Could not start attach mechanism: No such file or directory
-```
-The profiler cannot establish communication with the target JVM through UNIX domain socket.
-
-Usually this happens in one of the following cases:
- 1. Attach socket `/tmp/.java_pidNNN` has been deleted. It is a common
- practice to clean `/tmp` automatically with some scheduled script.
- Configure the cleanup software to exclude `.java_pid*` files from deletion.  
- How to check: run `lsof -p PID | grep java_pid`  
- If it lists a socket file, but the file does not exist, then this is exactly
- the described problem.
- 2. JVM is started with `-XX:+DisableAttachMechanism` option.
- 3. `/tmp` directory of Java process is not physically the same directory
- as `/tmp` of your shell, because Java is running in a container or in
- `chroot` environment. `jattach` attempts to solve this automatically,
- but it might lack the required permissions to do so.  
- Check `strace build/jattach PID properties`
- 4. JVM is busy and cannot reach a safepoint. For instance,
- JVM is in the middle of long-running garbage collection.  
- How to check: run `kill -3 PID`. Healthy JVM process should print
- a thread dump and heap info in its console.
-
-```
-Failed to inject profiler into <pid>
-```
-The connection with the target JVM has been established, but JVM is unable to load profiler shared library.
-Make sure the user of JVM process has permissions to access `libasyncProfiler.so` by exactly the same absolute path.
-For more information see [#78](https://github.com/jvm-profiling-tools/async-profiler/issues/78).
-
-```
-Perf events unavailble. See stderr of the target process.
-```
-`perf_event_open()` syscall has failed. The error message is printed to the error stream
-of the target JVM.
-
-Typical reasons include:
- 1. `/proc/sys/kernel/perf_event_paranoid` is set to restricted mode (>=2).
- 2. seccomp disables perf_event_open API in a container.
- 3. OS runs under a hypervisor that does not virtualize performance counters.
- 4. perf_event_open API is not supported on this system, e.g. WSL.
-
-If changing the configuration is not possible, you may fall back to
-`-e itimer` profiling mode. It is similar to `cpu` mode, but does not
-require perf_events support. As a drawback, there will be no kernel
-stack traces. 
-
-```
-No AllocTracer symbols found. Are JDK debug symbols installed?
-```
-It might be needed to install the package with OpenJDK debug symbols.
-See [Allocation profiling](#allocation-profiling) for details.
-
-Note that allocation profiling is not supported on JVMs other than HotSpot, e.g. Zing.
-
-```
-VMStructs unavailable. Unsupported JVM?
-```
-JVM shared library does not export `gHotSpotVMStructs*` symbols -
-apparently this is not a HotSpot JVM. Sometimes the same message
-can be also caused by an incorrectly built JDK
-(see [#218](https://github.com/jvm-profiling-tools/async-profiler/issues/218)).
-In these cases installing JDK debug symbols may solve the problem.
-
-```
-[frame_buffer_overflow]
-```
-This message in the output means there was not enough space to store all call traces.
-Consider increasing frame buffer size with `-b` option.

docs/cddl1.txt

@@ -1,358 +0,0 @@
-COMMON DEVELOPMENT AND DISTRIBUTION LICENSE (CDDL) Version 1.0
-
-      1. Definitions.
-      
-            1.1. "Contributor" means each individual or entity that
-            creates or contributes to the creation of Modifications.
-            
-            1.2. "Contributor Version" means the combination of the
-            Original Software, prior Modifications used by a
-            Contributor (if any), and the Modifications made by that
-            particular Contributor.
-            
-            1.3. "Covered Software" means (a) the Original Software, or
-            (b) Modifications, or (c) the combination of files
-            containing Original Software with files containing
-            Modifications, in each case including portions thereof.
-            
-            1.4. "Executable" means the Covered Software in any form
-            other than Source Code. 
-            
-            1.5. "Initial Developer" means the individual or entity
-            that first makes Original Software available under this
-            License. 
-            
-            1.6. "Larger Work" means a work which combines Covered
-            Software or portions thereof with code not governed by the
-            terms of this License.
-            
-            1.7. "License" means this document.
-            
-            1.8. "Licensable" means having the right to grant, to the
-            maximum extent possible, whether at the time of the initial
-            grant or subsequently acquired, any and all of the rights
-            conveyed herein.
-            
-            1.9. "Modifications" means the Source Code and Executable
-            form of any of the following: 
-                  A. Any file that results from an addition to,
-                  deletion from or modification of the contents of a
-                  file containing Original Software or previous
-                  Modifications; 
-                  B. Any new file that contains any part of the
-                  Original Software or previous Modification; or 
-                  C. Any new file that is contributed or otherwise made
-                  available under the terms of this License.
-            
-            1.10. "Original Software" means the Source Code and
-            Executable form of computer software code that is
-            originally released under this License. 
-            
-            1.11. "Patent Claims" means any patent claim(s), now owned
-            or hereafter acquired, including without limitation,
-            method, process, and apparatus claims, in any patent
-            Licensable by grantor. 
-            
-            1.12. "Source Code" means (a) the common form of computer
-            software code in which modifications are made and (b)
-            associated documentation included in or with such code.
-            
-            1.13. "You" (or "Your") means an individual or a legal
-            entity exercising rights under, and complying with all of
-            the terms of, this License. For legal entities, "You"
-            includes any entity which controls, is controlled by, or is
-            under common control with You. For purposes of this
-            definition, "control" means (a) the power, direct or
-            indirect, to cause the direction or management of such
-            entity, whether by contract or otherwise, or (b) ownership
-            of more than fifty percent (50%) of the outstanding shares
-            or beneficial ownership of such entity.
-
-      2. License Grants. 
-      
-            2.1. The Initial Developer Grant.
-            Conditioned upon Your compliance with Section 3.1 below and
-            subject to third party intellectual property claims, the
-            Initial Developer hereby grants You a world-wide,
-            royalty-free, non-exclusive license: 
-                  (a) under intellectual property rights (other than
-                  patent or trademark) Licensable by Initial Developer,
-                  to use, reproduce, modify, display, perform,
-                  sublicense and distribute the Original Software (or
-                  portions thereof), with or without Modifications,
-                  and/or as part of a Larger Work; and 
-                  (b) under Patent Claims infringed by the making,
-                  using or selling of Original Software, to make, have
-                  made, use, practice, sell, and offer for sale, and/or
-                  otherwise dispose of the Original Software (or
-                  portions thereof). 
-                  (c) The licenses granted in Sections 2.1(a) and (b)
-                  are effective on the date Initial Developer first
-                  distributes or otherwise makes the Original Software
-                  available to a third party under the terms of this
-                  License. 
-                  (d) Notwithstanding Section 2.1(b) above, no patent
-                  license is granted: (1) for code that You delete from
-                  the Original Software, or (2) for infringements
-                  caused by: (i) the modification of the Original
-                  Software, or (ii) the combination of the Original
-                  Software with other software or devices. 
-            
-            2.2. Contributor Grant.
-            Conditioned upon Your compliance with Section 3.1 below and
-            subject to third party intellectual property claims, each
-            Contributor hereby grants You a world-wide, royalty-free,
-            non-exclusive license:
-                  (a) under intellectual property rights (other than
-                  patent or trademark) Licensable by Contributor to
-                  use, reproduce, modify, display, perform, sublicense
-                  and distribute the Modifications created by such
-                  Contributor (or portions thereof), either on an
-                  unmodified basis, with other Modifications, as
-                  Covered Software and/or as part of a Larger Work; and
-                  (b) under Patent Claims infringed by the making,
-                  using, or selling of Modifications made by that
-                  Contributor either alone and/or in combination with
-                  its Contributor Version (or portions of such
-                  combination), to make, use, sell, offer for sale,
-                  have made, and/or otherwise dispose of: (1)
-                  Modifications made by that Contributor (or portions
-                  thereof); and (2) the combination of Modifications
-                  made by that Contributor with its Contributor Version
-                  (or portions of such combination). 
-                  (c) The licenses granted in Sections 2.2(a) and
-                  2.2(b) are effective on the date Contributor first
-                  distributes or otherwise makes the Modifications
-                  available to a third party. 
-                  (d) Notwithstanding Section 2.2(b) above, no patent
-                  license is granted: (1) for any code that Contributor
-                  has deleted from the Contributor Version; (2) for
-                  infringements caused by: (i) third party
-                  modifications of Contributor Version, or (ii) the
-                  combination of Modifications made by that Contributor
-                  with other software (except as part of the
-                  Contributor Version) or other devices; or (3) under
-                  Patent Claims infringed by Covered Software in the
-                  absence of Modifications made by that Contributor. 
-
-      3. Distribution Obligations.
-      
-            3.1. Availability of Source Code.
-            Any Covered Software that You distribute or otherwise make
-            available in Executable form must also be made available in
-            Source Code form and that Source Code form must be
-            distributed only under the terms of this License. You must
-            include a copy of this License with every copy of the
-            Source Code form of the Covered Software You distribute or
-            otherwise make available. You must inform recipients of any
-            such Covered Software in Executable form as to how they can
-            obtain such Covered Software in Source Code form in a
-            reasonable manner on or through a medium customarily used
-            for software exchange.
-            
-            3.2. Modifications.
-            The Modifications that You create or to which You
-            contribute are governed by the terms of this License. You
-            represent that You believe Your Modifications are Your
-            original creation(s) and/or You have sufficient rights to
-            grant the rights conveyed by this License.
-            
-            3.3. Required Notices.
-            You must include a notice in each of Your Modifications
-            that identifies You as the Contributor of the Modification.
-            You may not remove or alter any copyright, patent or
-            trademark notices contained within the Covered Software, or
-            any notices of licensing or any descriptive text giving
-            attribution to any Contributor or the Initial Developer.
-            
-            3.4. Application of Additional Terms.
-            You may not offer or impose any terms on any Covered
-            Software in Source Code form that alters or restricts the
-            applicable version of this License or the recipients'
-            rights hereunder. You may choose to offer, and to charge a
-            fee for, warranty, support, indemnity or liability
-            obligations to one or more recipients of Covered Software.
-            However, you may do so only on Your own behalf, and not on
-            behalf of the Initial Developer or any Contributor. You
-            must make it absolutely clear that any such warranty,
-            support, indemnity or liability obligation is offered by
-            You alone, and You hereby agree to indemnify the Initial
-            Developer and every Contributor for any liability incurred
-            by the Initial Developer or such Contributor as a result of
-            warranty, support, indemnity or liability terms You offer.
-            
-            3.5. Distribution of Executable Versions.
-            You may distribute the Executable form of the Covered
-            Software under the terms of this License or under the terms
-            of a license of Your choice, which may contain terms
-            different from this License, provided that You are in
-            compliance with the terms of this License and that the
-            license for the Executable form does not attempt to limit
-            or alter the recipient's rights in the Source Code form
-            from the rights set forth in this License. If You
-            distribute the Covered Software in Executable form under a
-            different license, You must make it absolutely clear that
-            any terms which differ from this License are offered by You
-            alone, not by the Initial Developer or Contributor. You
-            hereby agree to indemnify the Initial Developer and every
-            Contributor for any liability incurred by the Initial
-            Developer or such Contributor as a result of any such terms
-            You offer.
-            
-            3.6. Larger Works.
-            You may create a Larger Work by combining Covered Software
-            with other code not governed by the terms of this License
-            and distribute the Larger Work as a single product. In such
-            a case, You must make sure the requirements of this License
-            are fulfilled for the Covered Software. 
-
-      4. Versions of the License. 
-      
-            4.1. New Versions.
-            Sun Microsystems, Inc. is the initial license steward and
-            may publish revised and/or new versions of this License
-            from time to time. Each version will be given a
-            distinguishing version number. Except as provided in
-            Section 4.3, no one other than the license steward has the
-            right to modify this License. 
-            
-            4.2. Effect of New Versions.
-            You may always continue to use, distribute or otherwise
-            make the Covered Software available under the terms of the
-            version of the License under which You originally received
-            the Covered Software. If the Initial Developer includes a
-            notice in the Original Software prohibiting it from being
-            distributed or otherwise made available under any
-            subsequent version of the License, You must distribute and
-            make the Covered Software available under the terms of the
-            version of the License under which You originally received
-            the Covered Software. Otherwise, You may also choose to
-            use, distribute or otherwise make the Covered Software
-            available under the terms of any subsequent version of the
-            License published by the license steward. 
-            
-            4.3. Modified Versions.
-            When You are an Initial Developer and You want to create a
-            new license for Your Original Software, You may create and
-            use a modified version of this License if You: (a) rename
-            the license and remove any references to the name of the
-            license steward (except to note that the license differs
-            from this License); and (b) otherwise make it clear that
-            the license contains terms which differ from this License.
-
-      5. DISCLAIMER OF WARRANTY.
-      
-      COVERED SOFTWARE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS"
-      BASIS, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
-      INCLUDING, WITHOUT LIMITATION, WARRANTIES THAT THE COVERED
-      SOFTWARE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR
-      PURPOSE OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND
-      PERFORMANCE OF THE COVERED SOFTWARE IS WITH YOU. SHOULD ANY
-      COVERED SOFTWARE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT THE
-      INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF
-      ANY NECESSARY SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF
-      WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS LICENSE. NO USE OF
-      ANY COVERED SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER THIS
-      DISCLAIMER. 
-
-      6. TERMINATION. 
-      
-            6.1. This License and the rights granted hereunder will
-            terminate automatically if You fail to comply with terms
-            herein and fail to cure such breach within 30 days of
-            becoming aware of the breach. Provisions which, by their
-            nature, must remain in effect beyond the termination of
-            this License shall survive.
-            
-            6.2. If You assert a patent infringement claim (excluding
-            declaratory judgment actions) against Initial Developer or
-            a Contributor (the Initial Developer or Contributor against
-            whom You assert such claim is referred to as "Participant")
-            alleging that the Participant Software (meaning the
-            Contributor Version where the Participant is a Contributor
-            or the Original Software where the Participant is the
-            Initial Developer) directly or indirectly infringes any
-            patent, then any and all rights granted directly or
-            indirectly to You by such Participant, the Initial
-            Developer (if the Initial Developer is not the Participant)
-            and all Contributors under Sections 2.1 and/or 2.2 of this
-            License shall, upon 60 days notice from Participant
-            terminate prospectively and automatically at the expiration
-            of such 60 day notice period, unless if within such 60 day
-            period You withdraw Your claim with respect to the
-            Participant Software against such Participant either
-            unilaterally or pursuant to a written agreement with
-            Participant.
-            
-            6.3. In the event of termination under Sections 6.1 or 6.2
-            above, all end user licenses that have been validly granted
-            by You or any distributor hereunder prior to termination
-            (excluding licenses granted to You by any distributor)
-            shall survive termination.
-
-      7. LIMITATION OF LIABILITY.
-      
-      UNDER NO CIRCUMSTANCES AND UNDER NO LEGAL THEORY, WHETHER TORT
-      (INCLUDING NEGLIGENCE), CONTRACT, OR OTHERWISE, SHALL YOU, THE
-      INITIAL DEVELOPER, ANY OTHER CONTRIBUTOR, OR ANY DISTRIBUTOR OF
-      COVERED SOFTWARE, OR ANY SUPPLIER OF ANY OF SUCH PARTIES, BE
-      LIABLE TO ANY PERSON FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR
-      CONSEQUENTIAL DAMAGES OF ANY CHARACTER INCLUDING, WITHOUT
-      LIMITATION, DAMAGES FOR LOST PROFITS, LOSS OF GOODWILL, WORK
-      STOPPAGE, COMPUTER FAILURE OR MALFUNCTION, OR ANY AND ALL OTHER
-      COMMERCIAL DAMAGES OR LOSSES, EVEN IF SUCH PARTY SHALL HAVE BEEN
-      INFORMED OF THE POSSIBILITY OF SUCH DAMAGES. THIS LIMITATION OF
-      LIABILITY SHALL NOT APPLY TO LIABILITY FOR DEATH OR PERSONAL
-      INJURY RESULTING FROM SUCH PARTY'S NEGLIGENCE TO THE EXTENT
-      APPLICABLE LAW PROHIBITS SUCH LIMITATION. SOME JURISDICTIONS DO
-      NOT ALLOW THE EXCLUSION OR LIMITATION OF INCIDENTAL OR
-      CONSEQUENTIAL DAMAGES, SO THIS EXCLUSION AND LIMITATION MAY NOT
-      APPLY TO YOU.
-
-      8. U.S. GOVERNMENT END USERS.
-      
-      The Covered Software is a "commercial item," as that term is
-      defined in 48 C.F.R. 2.101 (Oct. 1995), consisting of "commercial
-      computer software" (as that term is defined at 48 C.F.R. ¤
-      252.227-7014(a)(1)) and "commercial computer software
-      documentation" as such terms are used in 48 C.F.R. 12.212 (Sept.
-      1995). Consistent with 48 C.F.R. 12.212 and 48 C.F.R. 227.7202-1
-      through 227.7202-4 (June 1995), all U.S. Government End Users
-      acquire Covered Software with only those rights set forth herein.
-      This U.S. Government Rights clause is in lieu of, and supersedes,
-      any other FAR, DFAR, or other clause or provision that addresses
-      Government rights in computer software under this License.
-
-      9. MISCELLANEOUS.
-      
-      This License represents the complete agreement concerning subject
-      matter hereof. If any provision of this License is held to be
-      unenforceable, such provision shall be reformed only to the
-      extent necessary to make it enforceable. This License shall be
-      governed by the law of the jurisdiction specified in a notice
-      contained within the Original Software (except to the extent
-      applicable law, if any, provides otherwise), excluding such
-      jurisdiction's conflict-of-law provisions. Any litigation
-      relating to this License shall be subject to the jurisdiction of
-      the courts located in the jurisdiction and venue specified in a
-      notice contained within the Original Software, with the losing
-      party responsible for costs, including, without limitation, court
-      costs and reasonable attorneys' fees and expenses. The
-      application of the United Nations Convention on Contracts for the
-      International Sale of Goods is expressly excluded. Any law or
-      regulation which provides that the language of a contract shall
-      be construed against the drafter shall not apply to this License.
-      You agree that You alone are responsible for compliance with the
-      United States export administration regulations (and the export
-      control laws and regulation of any other countries) when You use,
-      distribute or otherwise make available any Covered Software.
-
-      10. RESPONSIBILITY FOR CLAIMS.
-      
-      As between Initial Developer and the Contributors, each party is
-      responsible for claims and damages arising, directly or
-      indirectly, out of its utilization of rights under this License
-      and You agree to work with Initial Developer and Contributors to
-      distribute such responsibility on an equitable basis. Nothing
-      herein is intended or shall be deemed to constitute any admission
-      of liability.

pom.xml

@@ -0,0 +1,102 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>tools.profiler</groupId>
+    <artifactId>async-profiler</artifactId>
+    <version>1.8.3</version>
+    <packaging>jar</packaging>
+
+    <name>async-profiler</name>
+    <url>https://profiler.tools</url>
+    <description>Low overhead sampling profiler for Java</description>
+
+    <licenses>
+        <license>
+            <name>Apache License Version 2.0</name>
+            <url>http://www.apache.org/licenses/LICENSE-2.0</url>
+            <distribution>repo</distribution>
+        </license>
+    </licenses>
+    <scm>
+        <url>https://github.com/jvm-profiling-tools/async-profiler</url>
+        <connection>scm:git:git@github.com:jvm-profiling-tools/async-profiler.git</connection>
+        <developerConnection>scm:git:git@github.com:jvm-profiling-tools/async-profiler.git</developerConnection>
+    </scm>
+    <developers>
+        <developer>
+            <id>apangin</id>
+            <name>Andrei Pangin</name>
+            <email>noreply@pangin.pro</email>
+        </developer>
+    </developers>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <build>
+        <sourceDirectory>src/api</sourceDirectory>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.1</version>
+                <configuration>
+                    <source>1.6</source>
+                    <target>1.6</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-source-plugin</artifactId>
+                <version>3.2.0</version>
+                <executions>
+                    <execution>
+                        <id>attach-sources</id>
+                        <goals>
+                            <goal>jar-no-fork</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+                <version>3.2.0</version>
+                <executions>
+                    <execution>
+                        <id>attach-javadocs</id>
+                        <goals>
+                            <goal>jar</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-gpg-plugin</artifactId>
+                <version>1.6</version>
+                <executions>
+                    <execution>
+                        <id>sign-artifacts</id>
+                        <phase>verify</phase>
+                        <goals>
+                            <goal>sign</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <distributionManagement>
+        <snapshotRepository>
+            <id>ossrh</id>
+            <url>https://oss.sonatype.org/content/repositories/snapshots</url>
+        </snapshotRepository>
+        <repository>
+            <id>ossrh</id>
+            <url>https://oss.sonatype.org/service/local/staging/deploy/maven2</url>
+        </repository>
+    </distributionManagement>
+</project>

profiler.sh

@@ -1,4 +1,5 @@
-#!/bin/bash
+#!/bin/sh
+set -eu
 
 usage() {
     echo "Usage: $0 [action] [options] <pid>"
@@ -6,6 +7,8 @@ usage() {
     echo "  start             start profiling and return immediately"
     echo "  resume            resume profiling without resetting collected data"
     echo "  stop              stop profiling"
+    echo "  jstack            get a thread dump"
+    echo "  check             check if the specified profiling event is available"
     echo "  status            print profiling status"
     echo "  list              list profiling events supported by the target JVM"
     echo "  collect           collect profile for the specified period of time"
@@ -16,36 +19,40 @@ usage() {
     echo "  -f filename       dump output to <filename>"
     echo "  -i interval       sampling interval in nanoseconds"
     echo "  -j jstackdepth    maximum Java stack depth"
-    echo "  -b bufsize        frame buffer size"
     echo "  -t                profile different threads separately"
     echo "  -s                simple class names instead of FQN"
     echo "  -g                print method signatures"
     echo "  -a                annotate Java method names"
-    echo "  -o fmt            output format: summary|traces|flat|collapsed|svg|tree|jfr"
+    echo "  -o fmt            output format: flat|collapsed|html|tree|jfr"
+    echo "  -I include        output only stack traces containing the specified pattern"
+    echo "  -X exclude        exclude stack traces with the specified pattern"
     echo "  -v, --version     display version string"
     echo ""
-    echo "  --title string    SVG title"
-    echo "  --width px        SVG width"
-    echo "  --height px       SVG frame height"
-    echo "  --minwidth px     skip frames smaller than px"
+    echo "  --title string    FlameGraph title"
+    echo "  --minwidth pct    skip frames smaller than pct%"
     echo "  --reverse         generate stack-reversed FlameGraph / Call tree"
     echo ""
     echo "  --all-kernel      only include kernel-mode events"
     echo "  --all-user        only include user-mode events"
+    echo "  --cstack mode     how to traverse C stack: fp|lbr|no"
+    echo "  --begin function  begin profiling when function is executed"
+    echo "  --end function    end profiling when function is executed"
     echo ""
     echo "<pid> is a numeric process ID of the target JVM"
     echo "      or 'jps' keyword to find running JVM automatically"
+    echo "      or the application's name as it would appear in the jps tool"
     echo ""
     echo "Example: $0 -d 30 -f profile.svg 3456"
     echo "         $0 start -i 999000 jps"
-    echo "         $0 stop -o summary,flat jps"
+    echo "         $0 stop -o flat jps"
+    echo "         $0 -d 5 -e alloc MyAppName"
     exit 1
 }
 
 mirror_output() {
     # Mirror output from temporary file to local terminal
-    if [[ $USE_TMP ]]; then
-        if [[ -f $FILE ]]; then
+    if [ "$USE_TMP" = true ]; then
+        if [ -f "$FILE" ]; then
             cat "$FILE"
             rm "$FILE"
         fi
@@ -53,21 +60,23 @@ mirror_output() {
 }
 
 check_if_terminated() {
-    if ! kill -0 $PID 2> /dev/null; then
+    if ! kill -0 "$PID" 2> /dev/null; then
         mirror_output
         exit 0
     fi
 }
 
 jattach() {
-    "$JATTACH" $PID load "$PROFILER" true "$1" > /dev/null
+    set +e
+    "$JATTACH" "$PID" load "$PROFILER" true "$1" > /dev/null
     RET=$?
+    set -e
 
     # Check if jattach failed
     if [ $RET -ne 0 ]; then
         if [ $RET -eq 255 ]; then
             echo "Failed to inject profiler into $PID"
-            if [ "$UNAME_S" == "Darwin" ]; then
+            if [ "$(uname -s)" = "Darwin" ]; then
                 otool -L "$PROFILER"
             else
                 ldd "$PROFILER"
@@ -79,18 +88,8 @@ jattach() {
     mirror_output
 }
 
-function abspath() {
-    if [ "$UNAME_S" == "Darwin" ]; then
-        perl -MCwd -e 'print Cwd::abs_path shift' "$1"
-    else
-        readlink -f "$1"
-    fi
-}
-
-
 OPTIND=1
-UNAME_S=$(uname -s)
-SCRIPT_DIR=$(dirname "$(abspath "$0")")
+SCRIPT_DIR="$(cd "$(dirname "$0")" > /dev/null 2>&1; pwd -P)"
 JATTACH=$SCRIPT_DIR/build/jattach
 PROFILER=$SCRIPT_DIR/build/libasyncProfiler.so
 ACTION="collect"
@@ -98,27 +97,29 @@ EVENT="cpu"
 DURATION="60"
 FILE=""
 USE_TMP="true"
-INTERVAL=""
-JSTACKDEPTH=""
-FRAMEBUF=""
-THREADS=""
-RING=""
 OUTPUT=""
 FORMAT=""
+PARAMS=""
+PID=""
 
-while [[ $# -gt 0 ]]; do
+while [ $# -gt 0 ]; do
     case $1 in
         -h|"-?")
             usage
             ;;
-        start|resume|stop|status|list|collect)
+        start|resume|stop|check|status|list|collect)
             ACTION="$1"
             ;;
+        jstack)
+            ACTION="start"
+            EVENT="jstack"
+            PARAMS="$PARAMS,threads"
+            ;;
         -v|--version)
             ACTION="version"
             ;;
         -e)
-            EVENT="$2"
+            EVENT="$(echo "$2" | sed 's/,/,event=/g')"
             shift
             ;;
         -d)
@@ -127,23 +128,19 @@ while [[ $# -gt 0 ]]; do
             ;;
         -f)
             FILE="$2"
-            unset USE_TMP
+            USE_TMP=false
             shift
             ;;
         -i)
-            INTERVAL=",interval=$2"
+            PARAMS="$PARAMS,interval=$2"
             shift
             ;;
         -j)
-            JSTACKDEPTH=",jstackdepth=$2"
-            shift
-            ;;
-        -b)
-            FRAMEBUF=",framebuf=$2"
+            PARAMS="$PARAMS,jstackdepth=$2"
             shift
             ;;
         -t)
-            THREADS=",threads"
+            PARAMS="$PARAMS,threads"
             ;;
         -s)
             FORMAT="$FORMAT,simple"
@@ -158,27 +155,49 @@ while [[ $# -gt 0 ]]; do
             OUTPUT="$2"
             shift
             ;;
+        -I|--include)
+            FORMAT="$FORMAT,include=$2"
+            shift
+            ;;
+        -X|--exclude)
+            FORMAT="$FORMAT,exclude=$2"
+            shift
+            ;;
+        --filter)
+            FILTER="$(echo "$2" | sed 's/,/;/g')"
+            FORMAT="$FORMAT,filter=$FILTER"
+            shift
+            ;;
         --title)
             # escape XML special characters and comma
-            TITLE=${2//&/&amp;}
-            TITLE=${TITLE//</&lt;}
-            TITLE=${TITLE//>/&gt;}
-            TITLE=${TITLE//,/&#44;}
+            TITLE="$(echo "$2" | sed 's/&/\&amp;/g; s/</\&lt;/g; s/>/\&gt;/g; s/,/\&#44;/g')"
             FORMAT="$FORMAT,title=$TITLE"
             shift
             ;;
         --width|--height|--minwidth)
-            FORMAT="$FORMAT,${1:2}=$2"
+            FORMAT="$FORMAT,${1#--}=$2"
             shift
             ;;
         --reverse)
             FORMAT="$FORMAT,reverse"
             ;;
         --all-kernel)
-            RING=",allkernel"
+            PARAMS="$PARAMS,allkernel"
             ;;
         --all-user)
-            RING=",alluser"
+            PARAMS="$PARAMS,alluser"
+            ;;
+        --cstack|--call-graph)
+            PARAMS="$PARAMS,cstack=$2"
+            shift
+            ;;
+        --begin|--end)
+            PARAMS="$PARAMS,${1#--}=$2"
+            shift
+            ;;
+        --safe-mode)
+            PARAMS="$PARAMS,safemode=$2"
+            shift
             ;;
         [0-9]*)
             PID="$1"
@@ -187,31 +206,53 @@ while [[ $# -gt 0 ]]; do
             # A shortcut for getting PID of a running Java application
             # -XX:+PerfDisableSharedMem prevents jps from appearing in its own list
             PID=$(pgrep -n java || jps -q -J-XX:+PerfDisableSharedMem)
+            if [ "$PID" = "" ]; then
+                echo "No Java process could be found!"
+            fi
             ;;
-        *)
+        -*)
             echo "Unrecognized option: $1"
             usage
             ;;
+        *)
+            if [ $# -eq 1 ]; then
+                # the last argument is the application name as it would appear in the jps tool
+                PID=$(jps -J-XX:+PerfDisableSharedMem | grep " $1$" | head -n 1 | cut -d ' ' -f 1)
+                if [ "$PID" = "" ]; then
+                    echo "No Java process '$1' could be found!"
+                fi
+            else
+                echo "Unrecognized option: $1"
+                usage
+            fi
+            ;;
     esac
     shift
 done
 
-if [[ "$PID" == "" && "$ACTION" != "version" ]]; then
+if [ "$PID" = "" ] && [ "$ACTION" != "version" ]; then
     usage
 fi
 
 # If no -f argument is given, use temporary file to transfer output to caller terminal.
 # Let the target process create the file in case this script is run by superuser.
-if [[ $USE_TMP ]]; then
+if [ "$USE_TMP" = true ]; then
     FILE=/tmp/async-profiler.$$.$PID
-elif [[ $FILE != /* ]]; then
-    # Output file is written by the target process. Make the path absolute to avoid confusion.
-    FILE=$PWD/$FILE
+else
+    case "$FILE" in
+        /*)
+            # Path is absolute
+            ;;
+        *)
+            # Output file is written by the target process. Make the path absolute to avoid confusion.
+            FILE=$PWD/$FILE
+            ;;
+    esac
 fi
 
 case $ACTION in
-    start|resume)
-        jattach "$ACTION,event=$EVENT,file=$FILE$INTERVAL$JSTACKDEPTH$FRAMEBUF$THREADS$RING,$OUTPUT$FORMAT"
+    start|resume|check)
+        jattach "$ACTION,event=$EVENT,file=$FILE,$OUTPUT$FORMAT$PARAMS"
         ;;
     stop)
         jattach "stop,file=$FILE,$OUTPUT$FORMAT"
@@ -223,18 +264,19 @@ case $ACTION in
         jattach "list,file=$FILE"
         ;;
     collect)
-        jattach "start,event=$EVENT,file=$FILE$INTERVAL$JSTACKDEPTH$FRAMEBUF$THREADS$RING,$OUTPUT$FORMAT"
-        while (( DURATION-- > 0 )); do
+        jattach "start,event=$EVENT,file=$FILE,$OUTPUT$FORMAT$PARAMS"
+        while [ "$DURATION" -gt 0 ]; do
+            DURATION=$(( DURATION-1 ))
             check_if_terminated
             sleep 1
         done
         jattach "stop,file=$FILE,$OUTPUT$FORMAT"
         ;;
     version)
-        if [[ "$PID" == "" ]]; then
-            java "-agentpath:$PROFILER=version" -version 2> /dev/null
+        if [ "$PID" = "" ]; then
+            java "-agentpath:$PROFILER=version=full" -version 2> /dev/null
         else
-            jattach "version,file=$FILE"
+            jattach "version=full,file=$FILE"
         fi
         ;;
 esac

src/allocTracer.cpp

@@ -14,8 +14,6 @@
  * limitations under the License.
  */
 
-#include <unistd.h>
-#include <sys/mman.h>
 #include "allocTracer.h"
 #include "os.h"
 #include "profiler.h"
@@ -23,85 +21,56 @@
 #include "vmStructs.h"
 
 
-// JDK 7-9
-Trap AllocTracer::_in_new_tlab("_ZN11AllocTracer33send_allocation_in_new_tlab_event");
-Trap AllocTracer::_outside_tlab("_ZN11AllocTracer34send_allocation_outside_tlab_event");
-// JDK 10+
-Trap AllocTracer::_in_new_tlab2("_ZN11AllocTracer27send_allocation_in_new_tlab");
-Trap AllocTracer::_outside_tlab2("_ZN11AllocTracer28send_allocation_outside_tlab");
+int AllocTracer::_trap_kind;
+Trap AllocTracer::_in_new_tlab;
+Trap AllocTracer::_outside_tlab;
 
 u64 AllocTracer::_interval;
 volatile u64 AllocTracer::_allocated_bytes;
 
 
-// Resolve the address of the intercepted function
-bool Trap::resolve(NativeCodeCache* libjvm) {
-    if (_entry != NULL) {
-        return true;
-    }
-
-    _entry = (instruction_t*)libjvm->findSymbolByPrefix(_func_name);
-    if (_entry != NULL) {
-        // Make the entry point writable, so we can rewrite instructions
-        long page_size = sysconf(_SC_PAGESIZE);
-        uintptr_t page_start = (uintptr_t)_entry & -page_size;
-        mprotect((void*)page_start, page_size, PROT_READ | PROT_WRITE | PROT_EXEC);
-        return true;
-    }
-
-    return false;
-}
-
-// Insert breakpoint at the very first instruction
-void Trap::install() {
-    if (_entry != NULL) {
-        _saved_insn = *_entry;
-        *_entry = BREAKPOINT;
-        flushCache(_entry);
-    }
-}
-
-// Clear breakpoint - restore the original instruction
-void Trap::uninstall() {
-    if (_entry != NULL) {
-        *_entry = _saved_insn;
-        flushCache(_entry);
-    }
-}
-
-
 // Called whenever our breakpoint trap is hit
 void AllocTracer::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {
     StackFrame frame(ucontext);
+    int event_type;
+    uintptr_t total_size;
+    uintptr_t instance_size;
 
     // PC points either to BREAKPOINT instruction or to the next one
-    if (frame.pc() - (uintptr_t)_in_new_tlab._entry <= sizeof(instruction_t)) {
-        // send_allocation_in_new_tlab_event(KlassHandle klass, size_t tlab_size, size_t alloc_size)
-        recordAllocation(ucontext, frame.arg0(), frame.arg1(), false);
-    } else if (frame.pc() - (uintptr_t)_outside_tlab._entry <= sizeof(instruction_t)) {
-        // send_allocation_outside_tlab_event(KlassHandle klass, size_t alloc_size);
-        recordAllocation(ucontext, frame.arg0(), frame.arg1(), true);
-    } else if (frame.pc() - (uintptr_t)_in_new_tlab2._entry <= sizeof(instruction_t)) {
+    if (_in_new_tlab.covers(frame.pc())) {
         // send_allocation_in_new_tlab(Klass* klass, HeapWord* obj, size_t tlab_size, size_t alloc_size, Thread* thread)
-        recordAllocation(ucontext, frame.arg0(), frame.arg2(), false);
-    } else if (frame.pc() - (uintptr_t)_outside_tlab2._entry <= sizeof(instruction_t)) {
+        // send_allocation_in_new_tlab_event(KlassHandle klass, size_t tlab_size, size_t alloc_size)
+        event_type = BCI_ALLOC;
+        total_size = _trap_kind == 1 ? frame.arg2() : frame.arg1();
+        instance_size = _trap_kind == 1 ? frame.arg3() : frame.arg2();
+    } else if (_outside_tlab.covers(frame.pc())) {
         // send_allocation_outside_tlab(Klass* klass, HeapWord* obj, size_t alloc_size, Thread* thread)
-        recordAllocation(ucontext, frame.arg0(), frame.arg2(), true);
+        // send_allocation_outside_tlab_event(KlassHandle klass, size_t alloc_size);
+        event_type = BCI_ALLOC_OUTSIDE_TLAB;
+        total_size = _trap_kind == 1 ? frame.arg2() : frame.arg1();
+        instance_size = 0;
     } else {
-        // Not our trap; nothing to do
+        // Not our trap
         return;
     }
 
     // Leave the trapped function by simulating "ret" instruction
+    uintptr_t klass = frame.arg0();
     frame.ret();
+
+    if (_enabled) {
+        // TODO: _enabled also uses traps
+        recordAllocation(ucontext, event_type, klass, total_size, instance_size);
+    }
 }
 
-void AllocTracer::recordAllocation(void* ucontext, uintptr_t rklass, uintptr_t rsize, bool outside_tlab) {
+void AllocTracer::recordAllocation(void* ucontext, int event_type, uintptr_t rklass,
+                                   uintptr_t total_size, uintptr_t instance_size) {
     if (_interval) {
         // Do not record allocation unless allocated at least _interval bytes
         while (true) {
             u64 prev = _allocated_bytes;
-            u64 next = prev + rsize;
+            u64 next = prev + total_size;
             if (next < _interval) {
                 if (__sync_bool_compare_and_swap(&_allocated_bytes, prev, next)) {
                     return;
@@ -114,24 +83,52 @@ void AllocTracer::recordAllocation(void* ucontext, uintptr_t rklass, uintptr_t r
         }
     }
 
-    VMSymbol* symbol = VMKlass::fromHandle(rklass)->name();
-    if (outside_tlab) {
-        // Invert the last bit to distinguish jmethodID from the allocation in new TLAB
-        Profiler::_instance.recordSample(ucontext, rsize, BCI_SYMBOL_OUTSIDE_TLAB, (jmethodID)((uintptr_t)symbol ^ 1));
-    } else {
-        Profiler::_instance.recordSample(ucontext, rsize, BCI_SYMBOL, (jmethodID)symbol);
+    AllocEvent event;
+    event._class_id = 0;
+    event._total_size = total_size;
+    event._instance_size = instance_size;
+
+    if (VMStructs::hasClassNames()) {
+        VMSymbol* symbol = VMKlass::fromHandle(rklass)->name();
+        event._class_id = Profiler::_instance.classMap()->lookup(symbol->body(), symbol->length());
     }
+
+    Profiler::_instance.recordSample(ucontext, total_size, event_type, &event);
+}
+
+Error AllocTracer::check(Arguments& args) {
+    if (_in_new_tlab.entry() != 0 && _outside_tlab.entry() != 0) {
+        return Error::OK;
+    }
+
+    NativeCodeCache* libjvm = VMStructs::libjvm();
+    const void* ne;
+    const void* oe;
+
+    if ((ne = libjvm->findSymbolByPrefix("_ZN11AllocTracer27send_allocation_in_new_tlab")) != NULL &&
+        (oe = libjvm->findSymbolByPrefix("_ZN11AllocTracer28send_allocation_outside_tlab")) != NULL) {
+        _trap_kind = 1;  // JDK 10+
+    } else if ((ne = libjvm->findSymbolByPrefix("_ZN11AllocTracer33send_allocation_in_new_tlab_eventE11KlassHandleP8HeapWord")) != NULL &&
+               (oe = libjvm->findSymbolByPrefix("_ZN11AllocTracer34send_allocation_outside_tlab_eventE11KlassHandleP8HeapWord")) != NULL) {
+        _trap_kind = 1;  // JDK 8u262+
+    } else if ((ne = libjvm->findSymbolByPrefix("_ZN11AllocTracer33send_allocation_in_new_tlab_event")) != NULL &&
+               (oe = libjvm->findSymbolByPrefix("_ZN11AllocTracer34send_allocation_outside_tlab_event")) != NULL) {
+        _trap_kind = 2;  // JDK 7-9
+    } else {
+        return Error("No AllocTracer symbols found. Are JDK debug symbols installed?");
+    }
+
+    if (!_in_new_tlab.assign(ne) || !_outside_tlab.assign(oe)) {
+        return Error("Unable to install allocation trap");
+    }
+
+    return Error::OK;
 }
 
 Error AllocTracer::start(Arguments& args) {
-    if (!VMStructs::available()) {
-        return Error("VMStructs unavailable. Unsupported JVM?");
-    }
-
-    NativeCodeCache* libjvm = Profiler::_instance.jvmLibrary();
-    if (!(_in_new_tlab.resolve(libjvm) || _in_new_tlab2.resolve(libjvm)) ||
-        !(_outside_tlab.resolve(libjvm) || _outside_tlab2.resolve(libjvm))) {
-        return Error("No AllocTracer symbols found. Are JDK debug symbols installed?");
+    Error error = check(args);
+    if (error) {
+        return error;
     }
 
     _interval = args._interval;
@@ -141,8 +138,6 @@ Error AllocTracer::start(Arguments& args) {
 
     _in_new_tlab.install();
     _outside_tlab.install();
-    _in_new_tlab2.install();
-    _outside_tlab2.install();
 
     return Error::OK;
 }
@@ -150,6 +145,4 @@ Error AllocTracer::start(Arguments& args) {
 void AllocTracer::stop() {
     _in_new_tlab.uninstall();
     _outside_tlab.uninstall();
-    _in_new_tlab2.uninstall();
-    _outside_tlab2.uninstall();
 }

src/allocTracer.h

@@ -19,44 +19,23 @@
 
 #include <signal.h>
 #include <stdint.h>
-#include "arch.h"
-#include "codeCache.h"
 #include "engine.h"
-
-
-// Describes OpenJDK function being intercepted
-class Trap {
-  private:
-    const char* _func_name;
-    instruction_t* _entry;
-    instruction_t _saved_insn;
-
-  public:
-    Trap(const char* func_name) : _func_name(func_name), _entry(NULL) {
-    }
-
-    bool resolve(NativeCodeCache* libjvm);
-    void install();
-    void uninstall();
-
-    friend class AllocTracer;
-};
+#include "trap.h"
 
 
 class AllocTracer : public Engine {
   private:
-    // JDK 7-9
+    static int _trap_kind;
     static Trap _in_new_tlab;
     static Trap _outside_tlab;
-    // JDK 10+
-    static Trap _in_new_tlab2;
-    static Trap _outside_tlab2;
 
     static u64 _interval;
     static volatile u64 _allocated_bytes;
 
     static void signalHandler(int signo, siginfo_t* siginfo, void* ucontext);
-    static void recordAllocation(void* ucontext, uintptr_t rklass, uintptr_t rsize, bool outside_tlab); 
+
+    static void recordAllocation(void* ucontext, int event_type, uintptr_t rklass,
+                                 uintptr_t total_size, uintptr_t instance_size);
 
   public:
     const char* name() {
@@ -67,6 +46,11 @@ class AllocTracer : public Engine {
         return "bytes";
     }
 
+    CStack cstack() {
+        return CSTACK_NO;
+    }
+
+    Error check(Arguments& args);
     Error start(Arguments& args);
     void stop();
 };

src/api/one/profiler/AsyncProfiler.java

@@ -16,6 +16,8 @@
 
 package one.profiler;
 
+import java.io.IOException;
+
 /**
  * Java API for in-process profiling. Serves as a wrapper around
  * async-profiler native library. This class is a singleton.
@@ -25,10 +27,7 @@ package one.profiler;
 public class AsyncProfiler implements AsyncProfilerMXBean {
     private static AsyncProfiler instance;
 
-    private final String version;
-
     private AsyncProfiler() {
-        this.version = version0();
     }
 
     public static AsyncProfiler getInstance() {
@@ -100,7 +99,11 @@ public class AsyncProfiler implements AsyncProfilerMXBean {
      */
     @Override
     public String getVersion() {
-        return version;
+        try {
+            return execute0("version");
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
     }
 
     /**
@@ -110,10 +113,10 @@ public class AsyncProfiler implements AsyncProfilerMXBean {
      * @param command Profiling command
      * @return The command result
      * @throws IllegalArgumentException If failed to parse the command
-     * @throws java.io.IOException If failed to create output file
+     * @throws IOException If failed to create output file
      */
     @Override
-    public String execute(String command) throws IllegalArgumentException, java.io.IOException {
+    public String execute(String command) throws IllegalArgumentException, IOException {
         return execute0(command);
     }
 
@@ -125,18 +128,11 @@ public class AsyncProfiler implements AsyncProfilerMXBean {
      */
     @Override
     public String dumpCollapsed(Counter counter) {
-        return dumpCollapsed0(counter.ordinal());
-    }
-
-    /**
-     * Dump collected stack traces
-     *
-     * @param maxTraces Maximum number of stack traces to dump. 0 means no limit
-     * @return Textual representation of the profile
-     */
-    @Override
-    public String dumpTraces(int maxTraces) {
-        return dumpTraces0(maxTraces);
+        try {
+            return execute0("collapsed,counter=" + counter.name().toLowerCase());
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
     }
 
     /**
@@ -147,14 +143,49 @@ public class AsyncProfiler implements AsyncProfilerMXBean {
      */
     @Override
     public String dumpFlat(int maxMethods) {
-        return dumpFlat0(maxMethods);
+        try {
+            return execute0("flat=" + maxMethods);
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    /**
+     * Add the given thread to the set of profiled threads.
+     * 'filter' option must be enabled to use this method.
+     *
+     * @param thread Thread to include in profiling
+     */
+    public void addThread(Thread thread) {
+        filterThread(thread, true);
+    }
+
+    /**
+     * Remove the given thread from the set of profiled threads.
+     * 'filter' option must be enabled to use this method.
+     *
+     * @param thread Thread to exclude from profiling
+     */
+    public void removeThread(Thread thread) {
+        filterThread(thread, false);
+    }
+
+    private void filterThread(Thread thread, boolean enable) {
+        if (thread == null) {
+            filterThread0(null, enable);
+        } else {
+            // Need to take lock to avoid race condition with a thread state change
+            synchronized (thread) {
+                Thread.State state = thread.getState();
+                if (state != Thread.State.NEW && state != Thread.State.TERMINATED) {
+                    filterThread0(thread, enable);
+                }
+            }
+        }
     }
 
     private native void start0(String event, long interval, boolean reset) throws IllegalStateException;
     private native void stop0() throws IllegalStateException;
-    private native String execute0(String command) throws IllegalArgumentException, java.io.IOException;
-    private native String dumpCollapsed0(int counter);
-    private native String dumpTraces0(int maxTraces);
-    private native String dumpFlat0(int maxMethods);
-    private native String version0();
+    private native String execute0(String command) throws IllegalArgumentException, IOException;
+    private native void filterThread0(Thread thread, boolean enable);
 }

src/api/one/profiler/AsyncProfilerMXBean.java

@@ -38,6 +38,5 @@ public interface AsyncProfilerMXBean {
     String execute(String command) throws IllegalArgumentException, java.io.IOException;
 
     String dumpCollapsed(Counter counter);
-    String dumpTraces(int maxTraces);
     String dumpFlat(int maxMethods);
 }

src/arch.h

@@ -18,6 +18,9 @@
 #define _ARCH_H
 
 
+typedef unsigned char u8;
+typedef unsigned short u16;
+typedef unsigned int u32;
 typedef unsigned long long u64;
 
 static inline u64 atomicInc(volatile u64& var, u64 increment = 1) {
@@ -34,6 +37,11 @@ static inline int atomicInc(volatile int& var, int increment = 1) {
 typedef unsigned char instruction_t;
 const instruction_t BREAKPOINT = 0xcc;
 
+const int SYSCALL_SIZE = 2;
+const int PLT_HEADER_SIZE = 16;
+const int PLT_ENTRY_SIZE = 16;
+const int PERF_REG_PC = 8;  // PERF_REG_X86_IP
+
 #define spinPause()       asm volatile("pause")
 #define rmb()             asm volatile("lfence" : : : "memory")
 #define flushCache(addr)  asm volatile("mfence; clflush (%0); mfence" : : "r"(addr) : "memory")
@@ -42,6 +50,12 @@ const instruction_t BREAKPOINT = 0xcc;
 
 typedef unsigned int instruction_t;
 const instruction_t BREAKPOINT = 0xe7f001f0;
+const instruction_t BREAKPOINT_THUMB = 0xde01de01;
+
+const int SYSCALL_SIZE = sizeof(instruction_t);
+const int PLT_HEADER_SIZE = 20;
+const int PLT_ENTRY_SIZE = 12;
+const int PERF_REG_PC = 15;  // PERF_REG_ARM_PC
 
 #define spinPause()       asm volatile("yield")
 #define rmb()             asm volatile("dmb ish" : : : "memory")
@@ -52,16 +66,18 @@ const instruction_t BREAKPOINT = 0xe7f001f0;
 typedef unsigned int instruction_t;
 const instruction_t BREAKPOINT = 0xd4200000;
 
+const int SYSCALL_SIZE = sizeof(instruction_t);
+const int PLT_HEADER_SIZE = 32;
+const int PLT_ENTRY_SIZE = 16;
+const int PERF_REG_PC = 32;  // PERF_REG_ARM64_PC
+
 #define spinPause()       asm volatile("yield")
 #define rmb()             asm volatile("dmb ish" : : : "memory")
 #define flushCache(addr)  __builtin___clear_cache((char*)(addr), (char*)(addr) + sizeof(instruction_t))
 
 #else
-#warning "Compiling on unsupported arch"
 
-#define spinPause()
-#define rmb()             __sync_synchronize()
-#define flushCache(addr)  __builtin___clear_cache((char*)(addr), (char*)(addr) + sizeof(instruction_t))
+#error "Compiling on unsupported arch"
 
 #endif
 

src/arguments.cpp

@@ -30,42 +30,60 @@ const Error Error::OK(NULL);
 // Extra buffer space for expanding file pattern
 const size_t EXTRA_BUF_SIZE = 512;
 
+// Statically compute hash code of a string containing up to 12 [a-z] letters
+#define HASH(s)    (HASH12(s "            "))
+
+#define HASH12(s)  (s[0] & 31LL)       | (s[1] & 31LL) <<  5 | (s[2]  & 31LL) << 10 | (s[3]  & 31LL) << 15 | \
+                   (s[4] & 31LL) << 20 | (s[5] & 31LL) << 25 | (s[6]  & 31LL) << 30 | (s[7]  & 31LL) << 35 | \
+                   (s[8] & 31LL) << 40 | (s[9] & 31LL) << 45 | (s[10] & 31LL) << 50 | (s[11] & 31LL) << 55
+
+// Simulate switch statement over string hashes
+#define SWITCH(arg)    long long arg_hash = hash(arg); if (0)
+
+#define CASE(s)        } else if (arg_hash == HASH(s)) {
+
+#define CASE2(s1, s2)  } else if (arg_hash == HASH(s1) || arg_hash == HASH(s2)) {
+
 
 // Parses agent arguments.
 // The format of the string is:
 //     arg[,arg...]
 // where arg is one of the following options:
-//     start         - start profiling
-//     resume        - start or resume profiling without resetting collected data
-//     stop          - stop profiling
-//     status        - print profiling status (inactive / running for X seconds)
-//     list          - show the list of available profiling events
-//     version       - display the agent version
-//     event=EVENT   - which event to trace (cpu, alloc, lock, cache-misses etc.)
-//     collapsed[=C] - dump collapsed stacks (the format used by FlameGraph script)
-//     svg[=C]       - produce Flame Graph in SVG format
-//     tree[=C]      - produce call tree in HTML format
-//                     C is counter type: 'samples' or 'total'
-//     jfr           - dump events in Java Flight Recorder format
-//     summary       - dump profiling summary (number of collected samples of each type)
-//     traces[=N]    - dump top N call traces
-//     flat[=N]      - dump top N methods (aka flat profile)
-//     interval=N    - sampling interval in ns (default: 10'000'000, i.e. 10 ms)
-//     jstackdepth=N - maximum Java stack depth (default: 2048)
-//     framebuf=N    - size of the buffer for stack frames (default: 1'000'000)
-//     threads       - profile different threads separately
-//     allkernel     - include only kernel-mode events
-//     alluser       - include only user-mode events
-//     simple        - simple class names instead of FQN
-//     dot           - dotted class names
-//     sig           - print method signatures
-//     ann           - annotate Java method names
-//     title=TITLE   - FlameGraph title
-//     width=PX      - FlameGraph image width
-//     height=PX     - FlameGraph frame height
-//     minwidth=PX   - FlameGraph minimum frame width
-//     reverse       - generate stack-reversed FlameGraph / Call tree
-//     file=FILENAME - output file name for dumping
+//     start           - start profiling
+//     resume          - start or resume profiling without resetting collected data
+//     stop            - stop profiling
+//     check           - check if the specified profiling event is available
+//     status          - print profiling status (inactive / running for X seconds)
+//     list            - show the list of available profiling events
+//     version[=full]  - display the agent version
+//     event=EVENT     - which event to trace (cpu, alloc, lock, cache-misses etc.)
+//     collapsed[=C]   - dump collapsed stacks (the format used by FlameGraph script)
+//     html[=C]        - produce Flame Graph in HTML format
+//     tree[=C]        - produce call tree in HTML format
+//                       C is counter type: 'samples' or 'total'
+//     jfr             - dump events in Java Flight Recorder format
+//     flat[=N]        - dump top N methods (aka flat profile)
+//     interval=N      - sampling interval in ns (default: 10'000'000, i.e. 10 ms)
+//     jstackdepth=N   - maximum Java stack depth (default: 2048)
+//     safemode=BITS   - disable stack recovery techniques (default: 0, i.e. everything enabled)
+//     file=FILENAME   - output file name for dumping
+//     filter=FILTER   - thread filter
+//     threads         - profile different threads separately
+//     cstack=MODE     - how to collect C stack frames in addition to Java stack
+//                       MODE is 'fp' (Frame Pointer), 'lbr' (Last Branch Record) or 'no'
+//     allkernel       - include only kernel-mode events
+//     alluser         - include only user-mode events
+//     simple          - simple class names instead of FQN
+//     dot             - dotted class names
+//     sig             - print method signatures
+//     ann             - annotate Java method names
+//     include=PATTERN - include stack traces containing PATTERN
+//     exclude=PATTERN - exclude stack traces containing PATTERN
+//     begin=FUNCTION  - begin profiling when FUNCTION is executed
+//     end=FUNCTION    - end profiling when FUNCTION is executed
+//     title=TITLE     - FlameGraph title
+//     minwidth=PCT    - FlameGraph minimum frame width in percent
+//     reverse         - generate stack-reversed FlameGraph / Call tree
 //
 // It is possible to specify multiple dump options at the same time
 
@@ -86,83 +104,136 @@ Error Arguments::parse(const char* args) {
         char* value = strchr(arg, '=');
         if (value != NULL) *value++ = 0;
 
-        if (strcmp(arg, "start") == 0) {
-            _action = ACTION_START;
-        } else if (strcmp(arg, "resume") == 0) {
-            _action = ACTION_RESUME;
-        } else if (strcmp(arg, "stop") == 0) {
-            _action = ACTION_STOP;
-        } else if (strcmp(arg, "status") == 0) {
-            _action = ACTION_STATUS;
-        } else if (strcmp(arg, "list") == 0) {
-            _action = ACTION_LIST;
-        } else if (strcmp(arg, "version") == 0) {
-            _action = ACTION_VERSION;
-        } else if (strcmp(arg, "event") == 0) {
-            if (value == NULL || value[0] == 0) {
-                return Error("event must not be empty");
-            }
-            _event = value;
-        } else if (strcmp(arg, "collapsed") == 0 || strcmp(arg, "folded") == 0) {
-            _output = OUTPUT_COLLAPSED;
-            _counter = value == NULL || strcmp(value, "samples") == 0 ? COUNTER_SAMPLES : COUNTER_TOTAL;
-        } else if (strcmp(arg, "flamegraph") == 0 || strcmp(arg, "svg") == 0) {
-            _output = OUTPUT_FLAMEGRAPH;
-            _counter = value == NULL || strcmp(value, "samples") == 0 ? COUNTER_SAMPLES : COUNTER_TOTAL;
-        } else if (strcmp(arg, "tree") == 0) {
-            _output = OUTPUT_TREE;
-            _counter = value == NULL || strcmp(value, "samples") == 0 ? COUNTER_SAMPLES : COUNTER_TOTAL;
-        } else if (strcmp(arg, "jfr") == 0) {
-            _output = OUTPUT_JFR;
-        } else if (strcmp(arg, "summary") == 0) {
-            _output = OUTPUT_TEXT;
-        } else if (strcmp(arg, "traces") == 0) {
-            _output = OUTPUT_TEXT;
-            _dump_traces = value == NULL ? INT_MAX : atoi(value);
-        } else if (strcmp(arg, "flat") == 0) {
-            _output = OUTPUT_TEXT;
-            _dump_flat = value == NULL ? INT_MAX : atoi(value);
-        } else if (strcmp(arg, "interval") == 0) {
-            if (value == NULL || (_interval = parseUnits(value)) <= 0) {
-                return Error("interval must be > 0");
-            }
-        } else if (strcmp(arg, "jstackdepth") == 0) {
-            if (value == NULL || (_jstackdepth = atoi(value)) <= 0) {
-                return Error("jstackdepth must be > 0");
-            }
-        } else if (strcmp(arg, "framebuf") == 0) {
-            if (value == NULL || (_framebuf = atoi(value)) <= 0) {
-                return Error("framebuf must be > 0");
-            }
-        } else if (strcmp(arg, "threads") == 0) {
-            _threads = true;
-        } else if (strcmp(arg, "allkernel") == 0) {
-            _ring = RING_KERNEL;
-        } else if (strcmp(arg, "alluser") == 0) {
-            _ring = RING_USER;
-        } else if (strcmp(arg, "simple") == 0) {
-            _style |= STYLE_SIMPLE;
-        } else if (strcmp(arg, "dot") == 0) {
-            _style |= STYLE_DOTTED;
-        } else if (strcmp(arg, "sig") == 0) {
-            _style |= STYLE_SIGNATURES;
-        } else if (strcmp(arg, "ann") == 0) {
-            _style |= STYLE_ANNOTATE;
-        } else if (strcmp(arg, "title") == 0 && value != NULL) {
-            _title = value;
-        } else if (strcmp(arg, "width") == 0 && value != NULL) {
-            _width = atoi(value);
-        } else if (strcmp(arg, "height") == 0 && value != NULL) {
-            _height = atoi(value);
-        } else if (strcmp(arg, "minwidth") == 0 && value != NULL) {
-            _minwidth = atof(value);
-        } else if (strcmp(arg, "reverse") == 0) {
-            _reverse = true;
-        } else if (strcmp(arg, "file") == 0) {
-            if (value == NULL || value[0] == 0) {
-                return Error("file must not be empty");
-            }
-            _file = value;
+        SWITCH (arg) {
+            // Actions
+            CASE("start")
+                _action = ACTION_START;
+
+            CASE("resume")
+                _action = ACTION_RESUME;
+
+            CASE("stop")
+                _action = ACTION_STOP;
+
+            CASE("check")
+                _action = ACTION_CHECK;
+
+            CASE("status")
+                _action = ACTION_STATUS;
+
+            CASE("list")
+                _action = ACTION_LIST;
+
+            CASE("version")
+                _action = value == NULL ? ACTION_VERSION : ACTION_FULL_VERSION;
+
+            // Output formats
+            CASE2("collapsed", "folded")
+                _output = OUTPUT_COLLAPSED;
+                _counter = value == NULL || strcmp(value, "samples") == 0 ? COUNTER_SAMPLES : COUNTER_TOTAL;
+
+            CASE2("flamegraph", "html")
+                _output = OUTPUT_FLAMEGRAPH;
+                _counter = value == NULL || strcmp(value, "samples") == 0 ? COUNTER_SAMPLES : COUNTER_TOTAL;
+
+            CASE("tree")
+                _output = OUTPUT_TREE;
+                _counter = value == NULL || strcmp(value, "samples") == 0 ? COUNTER_SAMPLES : COUNTER_TOTAL;
+
+            CASE("jfr")
+                _output = OUTPUT_JFR;
+
+            CASE("flat")
+                _output = OUTPUT_FLAT;
+                _dump_flat = value == NULL ? INT_MAX : atoi(value);
+
+            // Basic options
+            CASE("event")
+                if (value == NULL || value[0] == 0) {
+                    return Error("event must not be empty");
+                }
+
+                if (!addEvent(value)) {
+                    return Error("multiple incompatible events");
+                }
+
+            CASE("interval")
+                if (value == NULL || (_interval = parseUnits(value)) <= 0) {
+                    return Error("Invalid interval");
+                }
+
+            CASE("jstackdepth")
+                if (value == NULL || (_jstackdepth = atoi(value)) <= 0) {
+                    return Error("jstackdepth must be > 0");
+                }
+
+            CASE("safemode")
+                _safe_mode = value == NULL ? INT_MAX : atoi(value);
+
+            CASE("file")
+                if (value == NULL || value[0] == 0) {
+                    return Error("file must not be empty");
+                }
+                _file = value;
+
+            // Filters
+            CASE("filter")
+                _filter = value == NULL ? "" : value;
+
+            CASE("include")
+                if (value != NULL) appendToEmbeddedList(_include, value);
+
+            CASE("exclude")
+                if (value != NULL) appendToEmbeddedList(_exclude, value);
+
+            CASE("threads")
+                _threads = true;
+
+            CASE("allkernel")
+                _ring = RING_KERNEL;
+
+            CASE("alluser")
+                _ring = RING_USER;
+
+            CASE("cstack")
+                if (value != NULL) {
+                    if (value[0] == 'n') {
+                        _cstack = CSTACK_NO;
+                    } else if (value[0] == 'l') {
+                        _cstack = CSTACK_LBR;
+                    } else {
+                        _cstack = CSTACK_FP;
+                    }
+                }
+
+            // Output style modifiers
+            CASE("simple")
+                _style |= STYLE_SIMPLE;
+
+            CASE("dot")
+                _style |= STYLE_DOTTED;
+
+            CASE("sig")
+                _style |= STYLE_SIGNATURES;
+
+            CASE("ann")
+                _style |= STYLE_ANNOTATE;
+
+            CASE("begin")
+                _begin = value;
+
+            CASE("end")
+                _end = value;
+
+            // FlameGraph options
+            CASE("title")
+                if (value != NULL) _title = value;
+
+            CASE("minwidth")
+                if (value != NULL) _minwidth = atof(value);
+
+            CASE("reverse")
+                _reverse = true;
         }
     }
 
@@ -172,7 +243,6 @@ Error Arguments::parse(const char* args) {
 
     if (_file != NULL && _output == OUTPUT_NONE) {
         _output = detectOutputFormat(_file);
-        _dump_traces = 200;
         _dump_flat = 200;
     }
 
@@ -183,6 +253,36 @@ Error Arguments::parse(const char* args) {
     return Error::OK;
 }
 
+bool Arguments::addEvent(const char* event) {
+    if (strcmp(event, EVENT_ALLOC) == 0) {
+        _events |= EK_ALLOC;
+    } else if (strcmp(event, EVENT_LOCK) == 0) {
+        _events |= EK_LOCK;
+    } else {
+        if (_events & EK_CPU) {
+            return false;
+        }
+        _events |= EK_CPU;
+        _event_desc = event;
+    }
+    return true;
+}
+
+// The linked list of string offsets is embedded right into _buf array
+void Arguments::appendToEmbeddedList(int& list, char* value) {
+    ((int*)value)[-1] = list;
+    list = (int)(value - _buf);
+}
+
+// Should match statically computed HASH(arg)
+long long Arguments::hash(const char* arg) {
+    long long h = 0;
+    for (int shift = 0; *arg != 0; shift += 5) {
+        h |= (*arg++ & 31LL) << shift;
+    }
+    return h;
+}
+
 // Expands %p to the process id
 //         %t to the timestamp
 const char* Arguments::expandFilePattern(char* dest, size_t max_size, const char* pattern) {
@@ -218,45 +318,43 @@ const char* Arguments::expandFilePattern(char* dest, size_t max_size, const char
 Output Arguments::detectOutputFormat(const char* file) {
     const char* ext = strrchr(file, '.');
     if (ext != NULL) {
-        if (strcmp(ext, ".svg") == 0) {
+        if (strcmp(ext, ".html") == 0) {
             return OUTPUT_FLAMEGRAPH;
-        } else if (strcmp(ext, ".html") == 0) {
-            return OUTPUT_TREE;
         } else if (strcmp(ext, ".jfr") == 0) {
             return OUTPUT_JFR;
         } else if (strcmp(ext, ".collapsed") == 0 || strcmp(ext, ".folded") == 0) {
             return OUTPUT_COLLAPSED;
         }
     }
-    return OUTPUT_TEXT;
+    return OUTPUT_FLAT;
 }
 
 long Arguments::parseUnits(const char* str) {
     char* end;
     long result = strtol(str, &end, 0);
 
-    if (*end) {
-        switch (*end) {
-            case 'K': case 'k':
-            case 'U': case 'u': // microseconds
-                return result * 1000;
-            case 'M': case 'm': // million, megabytes or milliseconds
-                return result * 1000000;
-            case 'G': case 'g':
-            case 'S': case 's': // seconds
-                return result * 1000000000;
-        }
+    switch (*end) {
+        case 0:
+            return result;
+        case 'K': case 'k':
+        case 'U': case 'u': // microseconds
+            return result * 1000;
+        case 'M': case 'm': // million, megabytes or milliseconds
+            return result * 1000000;
+        case 'G': case 'g':
+        case 'S': case 's': // seconds
+            return result * 1000000000;
     }
 
-    return result;
+    return -1;
 }
 
 Arguments::~Arguments() {
-    free(_buf);
+    if (!_shared) free(_buf);
 }
 
 void Arguments::save(Arguments& other) {
-    free(_buf);
+    if (!_shared) free(_buf);
     *this = other;
-    other._buf = NULL;
+    other._shared = true;
 }

src/arguments.h

@@ -21,7 +21,6 @@
 
 
 const long DEFAULT_INTERVAL = 10000000;  // 10 ms
-const int DEFAULT_FRAMEBUF = 1000000;
 const int DEFAULT_JSTACKDEPTH = 2048;
 
 const char* const EVENT_CPU    = "cpu";
@@ -29,15 +28,18 @@ const char* const EVENT_ALLOC  = "alloc";
 const char* const EVENT_LOCK   = "lock";
 const char* const EVENT_WALL   = "wall";
 const char* const EVENT_ITIMER = "itimer";
+const char* const EVENT_JSTACK = "jstack";
 
 enum Action {
     ACTION_NONE,
     ACTION_START,
     ACTION_RESUME,
     ACTION_STOP,
+    ACTION_CHECK,
     ACTION_STATUS,
     ACTION_LIST,
     ACTION_VERSION,
+    ACTION_FULL_VERSION,
     ACTION_DUMP
 };
 
@@ -52,6 +54,12 @@ enum Ring {
     RING_USER
 };
 
+enum EventKind {
+    EK_CPU   = 1,
+    EK_ALLOC = 2,
+    EK_LOCK  = 4
+};
+
 enum Style {
     STYLE_SIMPLE     = 1,
     STYLE_DOTTED     = 2,
@@ -59,9 +67,16 @@ enum Style {
     STYLE_ANNOTATE   = 8
 };
 
+enum CStack {
+    CSTACK_DEFAULT,
+    CSTACK_NO,
+    CSTACK_FP,
+    CSTACK_LBR
+};
+
 enum Output {
     OUTPUT_NONE,
-    OUTPUT_TEXT,
+    OUTPUT_FLAT,
     OUTPUT_COLLAPSED,
     OUTPUT_FLAMEGRAPH,
     OUTPUT_TREE,
@@ -92,7 +107,11 @@ class Error {
 class Arguments {
   private:
     char* _buf;
+    bool _shared;
 
+    void appendToEmbeddedList(int& list, char* value);
+
+    static long long hash(const char* arg);
     static const char* expandFilePattern(char* dest, size_t max_size, const char* pattern);
     static Output detectOutputFormat(const char* file);
     static long parseUnits(const char* str);
@@ -101,42 +120,50 @@ class Arguments {
     Action _action;
     Counter _counter;
     Ring _ring;
-    const char* _event;
+    int _events;
+    const char* _event_desc;
     long _interval;
     int  _jstackdepth;
-    int _framebuf;
+    int _safe_mode;
+    const char* _file;
+    const char* _filter;
+    int _include;
+    int _exclude;
     bool _threads;
     int _style;
-    const char* _file;
+    CStack _cstack;
     Output _output;
-    int _dump_traces;
     int _dump_flat;
+    const char* _begin;
+    const char* _end;
     // FlameGraph parameters
     const char* _title;
-    int _width;
-    int _height;
     double _minwidth;
     bool _reverse;
 
     Arguments() :
         _buf(NULL),
+        _shared(false),
         _action(ACTION_NONE),
         _counter(COUNTER_SAMPLES),
         _ring(RING_ANY),
-        _event(EVENT_CPU),
+        _events(0),
+        _event_desc(NULL),
         _interval(0),
         _jstackdepth(DEFAULT_JSTACKDEPTH),
-        _framebuf(DEFAULT_FRAMEBUF),
+        _safe_mode(0),
+        _file(NULL),
+        _filter(NULL),
+        _include(0),
+        _exclude(0),
         _threads(false),
         _style(0),
-        _file(NULL),
+        _cstack(CSTACK_DEFAULT),
         _output(OUTPUT_NONE),
-        _dump_traces(0),
-        _dump_flat(0),
+        _begin(NULL),
+        _end(NULL),
         _title("Flame Graph"),
-        _width(1200),
-        _height(16),
-        _minwidth(0.25),
+        _minwidth(0),
         _reverse(false) {
     }
 
@@ -145,6 +172,11 @@ class Arguments {
     void save(Arguments& other);
 
     Error parse(const char* args);
+
+    bool addEvent(const char* event);
+
+    friend class FrameName;
+    friend class Recording;
 };
 
 #endif // _ARGUMENTS_H

src/callTraceStorage.cpp

@@ -0,0 +1,246 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <string.h>
+#include <unistd.h>
+#include "callTraceStorage.h"
+#include "os.h"
+
+
+static const u32 INITIAL_CAPACITY = 65536;
+static const u32 CALL_TRACE_CHUNK = 8 * 1024 * 1024;
+static const size_t PAGE_ALIGNMENT = sysconf(_SC_PAGESIZE) - 1;
+
+
+class LongHashTable {
+  private:
+    LongHashTable* _prev;
+    void* _padding0;
+    u32 _capacity;
+    u32 _padding1[15];
+    volatile u32 _size;
+    u32 _padding2[15];
+
+    static size_t getSize(u32 capacity) {
+        size_t size = sizeof(LongHashTable) + (sizeof(u64) + sizeof(CallTraceSample)) * capacity;
+        return (size + PAGE_ALIGNMENT) & ~PAGE_ALIGNMENT;
+    }
+
+  public:
+    static LongHashTable* allocate(LongHashTable* prev, u32 capacity) {
+        LongHashTable* table = (LongHashTable*)OS::safeAlloc(getSize(capacity));
+        if (table != NULL) {
+            table->_prev = prev;
+            table->_capacity = capacity;
+            table->_size = 0;
+        }
+        return table;
+    }
+
+    LongHashTable* destroy() {
+        LongHashTable* prev = _prev;
+        OS::safeFree(this, getSize(_capacity));
+        return prev;
+    }
+
+    LongHashTable* prev() {
+        return _prev;
+    }
+
+    u32 capacity() {
+        return _capacity;
+    }
+
+    u32 size() {
+        return _size;
+    }
+
+    u32 incSize() {
+        return __sync_add_and_fetch(&_size, 1);
+    }
+
+    u64* keys() {
+        return (u64*)(this + 1);
+    }
+
+    CallTraceSample* values() {
+        return (CallTraceSample*)(keys() + _capacity);
+    }
+
+    void clear() {
+        memset(keys(), 0, (sizeof(u64) + sizeof(CallTraceSample)) * _capacity);
+        _size = 0;
+    }
+};
+
+
+CallTraceStorage::CallTraceStorage() : _allocator(CALL_TRACE_CHUNK) {
+    _current_table = LongHashTable::allocate(NULL, INITIAL_CAPACITY);
+}
+
+CallTraceStorage::~CallTraceStorage() {
+    while (_current_table != NULL) {
+        _current_table = _current_table->destroy();
+    }
+}
+
+void CallTraceStorage::clear() {
+    while (_current_table->prev() != NULL) {
+        _current_table = _current_table->destroy();
+    }
+    _current_table->clear();
+    _allocator.clear();
+}
+
+void CallTraceStorage::collectTraces(std::map<u32, CallTrace*>& map) {
+    for (LongHashTable* table = _current_table; table != NULL; table = table->prev()) {
+        u64* keys = table->keys();
+        CallTraceSample* values = table->values();
+        u32 capacity = table->capacity();
+
+        for (u32 slot = 0; slot < capacity; slot++) {
+            if (keys[slot] != 0) {
+                map[capacity - (INITIAL_CAPACITY - 1) + slot] = values[slot].trace;
+            }
+        }
+    }
+}
+
+void CallTraceStorage::collectSamples(std::vector<CallTraceSample*>& samples) {
+    for (LongHashTable* table = _current_table; table != NULL; table = table->prev()) {
+        u64* keys = table->keys();
+        CallTraceSample* values = table->values();
+        u32 capacity = table->capacity();
+
+        for (u32 slot = 0; slot < capacity; slot++) {
+            if (keys[slot] != 0) {
+                samples.push_back(&values[slot]);
+            }
+        }
+    }
+}
+
+// Adaptation of MurmurHash64A by Austin Appleby
+u64 CallTraceStorage::calcHash(int num_frames, ASGCT_CallFrame* frames) {
+    const u64 M = 0xc6a4a7935bd1e995ULL;
+    const int R = 47;
+
+    int len = num_frames * sizeof(ASGCT_CallFrame);
+    u64 h = len * M;
+
+    const u64* data = (const u64*)frames;
+    const u64* end = data + len / 8;
+
+    while (data != end) {
+        u64 k = *data++;
+        k *= M;
+        k ^= k >> R;
+        k *= M;
+        h ^= k;
+        h *= M;
+    }
+
+    if (len & 4) {
+        h ^= *(u32*)data;
+        h *= M;
+    }
+
+    h ^= h >> R;
+    h *= M;
+    h ^= h >> R;
+
+    return h;
+}
+
+CallTrace* CallTraceStorage::storeCallTrace(int num_frames, ASGCT_CallFrame* frames) {
+    const size_t header_size = sizeof(CallTrace) - sizeof(ASGCT_CallFrame);
+    CallTrace* buf = (CallTrace*)_allocator.alloc(header_size + num_frames * sizeof(ASGCT_CallFrame));
+    if (buf != NULL) {
+        buf->num_frames = num_frames;
+        // Do not use memcpy inside signal handler
+        for (int i = 0; i < num_frames; i++) {
+            buf->frames[i] = frames[i];
+        }
+    }
+    return buf;
+}
+
+CallTrace* CallTraceStorage::findCallTrace(LongHashTable* table, u64 hash) {
+    u64* keys = table->keys();
+    u32 capacity = table->capacity();
+    u32 slot = hash & (capacity - 1);
+    u32 step = 0;
+
+    while (keys[slot] != hash) {
+        if (keys[slot] == 0) {
+            return NULL;
+        }
+        if (++step >= capacity) {
+            return NULL;
+        }
+        slot = (slot + step) & (capacity - 1);
+    }
+
+    return table->values()[slot].trace;
+}
+
+u32 CallTraceStorage::put(int num_frames, ASGCT_CallFrame* frames, u64 counter) {
+    u64 hash = calcHash(num_frames, frames);
+
+    LongHashTable* table = _current_table;
+    u64* keys = table->keys();
+    u32 capacity = table->capacity();
+    u32 slot = hash & (capacity - 1);
+    u32 step = 0;
+
+    while (keys[slot] != hash) {
+        if (keys[slot] == 0) {
+            if (!__sync_bool_compare_and_swap(&keys[slot], 0, hash)) {
+                continue;
+            }
+
+            // Increment the table size, and if the load factor exceeds 0.75, reserve a new table
+            if (table->incSize() == capacity * 3 / 4) {
+                LongHashTable* new_table = LongHashTable::allocate(table, capacity * 2);
+                if (new_table != NULL) {
+                    __sync_bool_compare_and_swap(&_current_table, table, new_table);
+                }
+            }
+
+            // Migrate from a previous table to save space
+            CallTrace* trace = table->prev() == NULL ? NULL : findCallTrace(table->prev(), hash);
+            if (trace == NULL) {
+                trace = storeCallTrace(num_frames, frames);
+            }
+            table->values()[slot].trace = trace;
+            break;
+        }
+
+        if (++step >= capacity) {
+            // Very unlikely case of a table overflow
+            return 0;
+        }
+        // Improved version of linear probing
+        slot = (slot + step) & (capacity - 1);
+    }
+
+    // TODO: check overhead
+    CallTraceSample& s = table->values()[slot];
+    atomicInc(s.samples);
+    atomicInc(s.counter, counter);
+
+    return capacity - (INITIAL_CAPACITY - 1) + slot;
+}

src/callTraceStorage.h

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _CALLTRACESTORAGE_H
+#define _CALLTRACESTORAGE_H
+
+#include <map>
+#include <vector>
+#include "arch.h"
+#include "linearAllocator.h"
+#include "vmEntry.h"
+
+
+class LongHashTable;
+
+struct CallTrace {
+    int num_frames;
+    ASGCT_CallFrame frames[1];
+};
+
+struct CallTraceSample {
+    CallTrace* trace;
+    u64 samples;
+    u64 counter;
+};
+
+class CallTraceStorage {
+  private:
+    LinearAllocator _allocator;
+    LongHashTable* _current_table;
+
+    u64 calcHash(int num_frames, ASGCT_CallFrame* frames);
+    CallTrace* storeCallTrace(int num_frames, ASGCT_CallFrame* frames);
+    CallTrace* findCallTrace(LongHashTable* table, u64 hash);
+
+  public:
+    CallTraceStorage();
+    ~CallTraceStorage();
+
+    void clear();
+    void collectTraces(std::map<u32, CallTrace*>& map);
+    void collectSamples(std::vector<CallTraceSample*>& samples);
+
+    u32 put(int num_frames, ASGCT_CallFrame* frames, u64 counter);
+};
+
+#endif // _CALLTRACESTORAGE

src/codeCache.cpp

@@ -22,21 +22,35 @@
 void CodeCache::expand() {
     CodeBlob* old_blobs = _blobs;
     CodeBlob* new_blobs = new CodeBlob[_capacity * 2];
-    memcpy(new_blobs, old_blobs, _capacity * sizeof(CodeBlob));
+
+    int live = 0;
+    for (int i = 0; i < _count; i++) {
+        if (_blobs[i]._method != NULL) {
+            new_blobs[live++] = _blobs[i];
+        }
+    }
+
+    _count = live;
     _capacity *= 2;
     _blobs = new_blobs;
     delete[] old_blobs;
 }
 
-void CodeCache::add(const void* start, int length, jmethodID method) {
+void CodeCache::add(const void* start, int length, jmethodID method, bool update_bounds) {
     if (_count >= _capacity) {
         expand();
     }
 
+    const void* end = (const char*)start + length;
     _blobs[_count]._start = start;
-    _blobs[_count]._end = (const char*)start + length;
+    _blobs[_count]._end = end;
     _blobs[_count]._method = method;
     _count++;
+
+    if (update_bounds) {
+        if (start < _min_address) _min_address = start;
+        if (end > _max_address) _max_address = end;
+    }
 }
 
 void CodeCache::remove(const void* start, jmethodID method) {
@@ -50,7 +64,8 @@ void CodeCache::remove(const void* start, jmethodID method) {
 
 jmethodID CodeCache::find(const void* address) {
     for (int i = 0; i < _count; i++) {
-        if (address >= _blobs[i]._start && address < _blobs[i]._end) {
+        CodeBlob* cb = _blobs + i;
+        if (address >= cb->_start && address < cb->_end && cb->_method != NULL) {
             return _blobs[i]._method;
         }
     }
@@ -71,8 +86,13 @@ NativeCodeCache::~NativeCodeCache() {
     free(_name);
 }
 
-void NativeCodeCache::add(const void* start, int length, const char* name) {
-    CodeCache::add(start, length, (jmethodID)strdup(name));
+void NativeCodeCache::add(const void* start, int length, const char* name, bool update_bounds) {
+    char* name_copy = strdup(name);
+    // Replace non-printable characters
+    for (char* s = name_copy; *s != 0; s++) {
+        if (*s < ' ') *s = '?';
+    }
+    CodeCache::add(start, length, (jmethodID)name_copy, update_bounds);
 }
 
 void NativeCodeCache::sort() {
@@ -80,8 +100,8 @@ void NativeCodeCache::sort() {
 
     qsort(_blobs, _count, sizeof(CodeBlob), CodeBlob::comparator);
 
-    if (_min_address == NULL) _min_address = _blobs[0]._start;
-    if (_max_address == NULL) _max_address = _blobs[_count - 1]._end;
+    if (_min_address == NO_MIN_ADDRESS) _min_address = _blobs[0]._start;
+    if (_max_address == NO_MAX_ADDRESS) _max_address = _blobs[_count - 1]._end;
 }
 
 const char* NativeCodeCache::binarySearch(const void* address) {
@@ -99,8 +119,9 @@ const char* NativeCodeCache::binarySearch(const void* address) {
         }
     }
 
-    // Symbols with zero size can be valid functions: e.g. ASM entry points or kernel code
-    if (low > 0 && _blobs[low - 1]._start == _blobs[low - 1]._end) {
+    // Symbols with zero size can be valid functions: e.g. ASM entry points or kernel code.
+    // Also, in some cases (endless loop) the return address may point beyond the function.
+    if (low > 0 && (_blobs[low - 1]._start == _blobs[low - 1]._end || _blobs[low - 1]._end == address)) {
         return (const char*)_blobs[low - 1]._method;
     }
     return _name;
@@ -117,7 +138,10 @@ const void* NativeCodeCache::findSymbol(const char* name) {
 }
 
 const void* NativeCodeCache::findSymbolByPrefix(const char* prefix) {
-    int prefix_len = strlen(prefix);
+    return findSymbolByPrefix(prefix, strlen(prefix));
+}
+
+const void* NativeCodeCache::findSymbolByPrefix(const char* prefix, int prefix_len) {
     for (int i = 0; i < _count; i++) {
         const char* blob_name = (const char*)_blobs[i]._method;
         if (blob_name != NULL && strncmp(blob_name, prefix, prefix_len) == 0) {

src/codeCache.h

@@ -20,6 +20,9 @@
 #include <jvmti.h>
 
 
+#define NO_MIN_ADDRESS  ((const void*)-1)
+#define NO_MAX_ADDRESS  ((const void*)0)
+
 const int INITIAL_CODE_CACHE_CAPACITY = 1000;
 
 
@@ -50,6 +53,8 @@ class CodeCache {
     int _capacity;
     int _count;
     CodeBlob* _blobs;
+    const void* _min_address;
+    const void* _max_address;
 
     void expand();
 
@@ -58,13 +63,19 @@ class CodeCache {
         _capacity = INITIAL_CODE_CACHE_CAPACITY;
         _count = 0;
         _blobs = new CodeBlob[_capacity];
+        _min_address = NO_MIN_ADDRESS;
+        _max_address = NO_MAX_ADDRESS;
     }
 
     ~CodeCache() {
         delete[] _blobs;
     }
 
-    void add(const void* start, int length, jmethodID method);
+    bool contains(const void* address) {
+        return address >= _min_address && address < _max_address;
+    }
+
+    void add(const void* start, int length, jmethodID method, bool update_bounds = false);
     void remove(const void* start, jmethodID method);
     jmethodID find(const void* address);
 };
@@ -73,11 +84,11 @@ class CodeCache {
 class NativeCodeCache : public CodeCache {
   private:
     char* _name;
-    const void* _min_address;
-    const void* _max_address;
-  
+
   public:
-    NativeCodeCache(const char* name, const void* min_address = NULL, const void* max_address = NULL);
+    NativeCodeCache(const char* name,
+                    const void* min_address = NO_MIN_ADDRESS,
+                    const void* max_address = NO_MAX_ADDRESS);
 
     ~NativeCodeCache();
 
@@ -85,15 +96,12 @@ class NativeCodeCache : public CodeCache {
         return _name;
     }
 
-    bool contains(const void* address) {
-        return address >= _min_address && address < _max_address;
-    }
-
-    void add(const void* start, int length, const char* name);
+    void add(const void* start, int length, const char* name, bool update_bounds = false);
     void sort();
     const char* binarySearch(const void* address);
     const void* findSymbol(const char* name);
     const void* findSymbolByPrefix(const char* prefix);
+    const void* findSymbolByPrefix(const char* prefix, int prefix_len);
 };
 
 #endif // _CODECACHE_H

src/converter/FlameGraph.java

@@ -0,0 +1,442 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.io.BufferedOutputStream;
+import java.io.BufferedReader;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.PrintStream;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.util.Map;
+import java.util.TreeMap;
+
+public class FlameGraph {
+    public String title = "Flame Graph";
+    public boolean reverse;
+    public double minwidth;
+    public int skip;
+    public String input;
+    public String output;
+
+    private final Frame root = new Frame();
+    private int depth;
+    private long mintotal;
+
+    public FlameGraph(String... args) {
+        for (int i = 0; i < args.length; i++) {
+            String arg = args[i];
+            if (!arg.startsWith("--") && !arg.isEmpty()) {
+                if (input == null) {
+                    input = arg;
+                } else {
+                    output = arg;
+                }
+            } else if (arg.equals("--title")) {
+                title = args[++i];
+            } else if (arg.equals("--reverse")) {
+                reverse = true;
+            } else if (arg.equals("--minwidth")) {
+                minwidth = Double.parseDouble(args[++i]);
+            } else if (arg.equals("--skip")) {
+                skip = Integer.parseInt(args[++i]);
+            }
+        }
+    }
+
+    public void parse() throws IOException {
+        parse(new InputStreamReader(new FileInputStream(input), StandardCharsets.UTF_8));
+    }
+
+    public void parse(Reader in) throws IOException {
+        try (BufferedReader br = new BufferedReader(in)) {
+            for (String line; (line = br.readLine()) != null; ) {
+                int space = line.lastIndexOf(' ');
+                if (space <= 0) continue;
+
+                String[] trace = line.substring(0, space).split(";");
+                long ticks = Long.parseLong(line.substring(space + 1));
+                addSample(trace, ticks);
+            }
+        }
+    }
+
+    public void addSample(String[] trace, long ticks) {
+        Frame frame = root;
+        if (reverse) {
+            for (int i = trace.length; --i >= skip; ) {
+                frame.total += ticks;
+                frame = frame.child(trace[i]);
+            }
+        } else {
+            for (int i = skip; i < trace.length; i++) {
+                frame.total += ticks;
+                frame = frame.child(trace[i]);
+            }
+        }
+        frame.total += ticks;
+        frame.self += ticks;
+
+        depth = Math.max(depth, trace.length);
+    }
+
+    public void dump() throws IOException {
+        if (output == null) {
+            dump(System.out);
+        } else {
+            try (BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(output), 32768);
+                 PrintStream out = new PrintStream(bos, false, "UTF-8")) {
+                dump(out);
+            }
+        }
+    }
+
+    public void dump(PrintStream out) {
+        out.print(applyReplacements(HEADER,
+                "{title}", title,
+                "{height}", (depth + 1) * 16,
+                "{depth}", depth + 1,
+                "{reverse}", reverse));
+
+        mintotal = (long) (root.total * minwidth / 100);
+        printFrame(out, "all", root, 0, 0);
+
+        out.print(FOOTER);
+    }
+
+    // Replace ${variables} in the given string with field values
+    private String applyReplacements(String s, Object... params) {
+        StringBuilder result = new StringBuilder(s.length() + 256);
+
+        int p = 0;
+        for (int q; (q = s.indexOf('$', p)) >= 0; ) {
+            result.append(s, p, q);
+            p = s.indexOf('}', q + 2) + 1;
+            String var = s.substring(q + 1, p);
+            for (int i = 0; i < params.length; i += 2) {
+                if (var.equals(params[i])) {
+                    result.append(params[i + 1]);
+                    break;
+                }
+            }
+        }
+
+        result.append(s, p, s.length());
+        return result.toString();
+    }
+
+    private void printFrame(PrintStream out, String title, Frame frame, int level, long x) {
+        int type = frameType(title);
+        title = stripSuffix(title);
+        if (title.indexOf('\'') >= 0) {
+            title = title.replace("'", "\\'");
+        }
+
+        out.println("f(" + level + "," + x + "," + frame.total + "," + type + ",'" + title + "')");
+
+        x += frame.self;
+        for (Map.Entry<String, Frame> e : frame.entrySet()) {
+            Frame child = e.getValue();
+            if (child.total >= mintotal) {
+                printFrame(out, e.getKey(), child, level + 1, x);
+            }
+            x += child.total;
+        }
+    }
+
+    private String stripSuffix(String title) {
+        int len = title.length();
+        if (len >= 4 && title.charAt(len - 1) == ']' && title.regionMatches(len - 4, "_[", 0, 2)) {
+            return title.substring(0, len - 4);
+        }
+        return title;
+    }
+
+    private int frameType(String title) {
+        if (title.endsWith("_[j]")) {
+            return 0;
+        } else if (title.endsWith("_[i]")) {
+            return 1;
+        } else if (title.endsWith("_[k]")) {
+            return 2;
+        } else if (title.contains("::") || title.startsWith("-[") || title.startsWith("+[")) {
+            return 3;
+        } else if (title.indexOf('/') > 0 || title.indexOf('.') > 0 && Character.isUpperCase(title.charAt(0))) {
+            return 0;
+        } else {
+            return 4;
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        FlameGraph fg = new FlameGraph(args);
+        if (fg.input == null) {
+            System.out.println("Usage: java " + FlameGraph.class.getName() + " [options] input.collapsed [output.html]");
+            System.out.println();
+            System.out.println("Options:");
+            System.out.println("  --title TITLE");
+            System.out.println("  --reverse");
+            System.out.println("  --minwidth PERCENT");
+            System.out.println("  --skip FRAMES");
+            System.exit(1);
+        }
+
+        fg.parse();
+        fg.dump();
+    }
+
+    static class Frame extends TreeMap<String, Frame> {
+        long total;
+        long self;
+
+        Frame child(String title) {
+            Frame child = get(title);
+            if (child == null) {
+                put(title, child = new Frame());
+            }
+            return child;
+        }
+    }
+
+    private static final String HEADER = "<!DOCTYPE html>\n" +
+            "<html lang='en'>\n" +
+            "<head>\n" +
+            "<meta charset='utf-8'>\n" +
+            "<style>\n" +
+            "\tbody {margin: 0; padding: 10px; background-color: #ffffff}\n" +
+            "\th1 {margin: 5px 0 0 0; font-size: 18px; font-weight: normal; text-align: center}\n" +
+            "\theader {margin: -24px 0 5px 0; line-height: 24px}\n" +
+            "\tbutton {font: 12px sans-serif; cursor: pointer}\n" +
+            "\tp {margin: 5px 0 5px 0}\n" +
+            "\ta {color: #0366d6}\n" +
+            "\t#hl {position: absolute; display: none; overflow: hidden; white-space: nowrap; pointer-events: none; background-color: #ffffe0; outline: 1px solid #ffc000; height: 15px}\n" +
+            "\t#hl span {padding: 0 3px 0 3px}\n" +
+            "\t#status {overflow: hidden; white-space: nowrap}\n" +
+            "\t#match {overflow: hidden; white-space: nowrap; display: none; float: right; text-align: right}\n" +
+            "\t#reset {cursor: pointer}\n" +
+            "</style>\n" +
+            "</head>\n" +
+            "<body style='font: 12px Verdana, sans-serif'>\n" +
+            "<h1>${title}</h1>\n" +
+            "<header style='text-align: left'><button id='reverse' title='Reverse'>&#x1f53b;</button>&nbsp;&nbsp;<button id='search' title='Search'>&#x1f50d;</button></header>\n" +
+            "<header style='text-align: right'>Produced by <a href='https://github.com/jvm-profiling-tools/async-profiler'>async-profiler</a></header>\n" +
+            "<canvas id='canvas' style='width: 100%; height: ${height}px'></canvas>\n" +
+            "<div id='hl'><span></span></div>\n" +
+            "<p id='match'>Matched: <span id='matchval'></span> <span id='reset' title='Clear'>&#x274c;</span></p>\n" +
+            "<p id='status'>&nbsp;</p>\n" +
+            "<script>\n" +
+            "\t// Copyright 2020 Andrei Pangin\n" +
+            "\t// Licensed under the Apache License, Version 2.0.\n" +
+            "\t'use strict';\n" +
+            "\tvar root, rootLevel, px, pattern;\n" +
+            "\tvar reverse = ${reverse};\n" +
+            "\tconst levels = Array(${depth});\n" +
+            "\tfor (let h = 0; h < levels.length; h++) {\n" +
+            "\t\tlevels[h] = [];\n" +
+            "\t}\n" +
+            "\n" +
+            "\tconst canvas = document.getElementById('canvas');\n" +
+            "\tconst c = canvas.getContext('2d');\n" +
+            "\tconst hl = document.getElementById('hl');\n" +
+            "\tconst status = document.getElementById('status');\n" +
+            "\n" +
+            "\tconst canvasWidth = canvas.offsetWidth;\n" +
+            "\tconst canvasHeight = canvas.offsetHeight;\n" +
+            "\tcanvas.style.width = canvasWidth + 'px';\n" +
+            "\tcanvas.width = canvasWidth * (devicePixelRatio || 1);\n" +
+            "\tcanvas.height = canvasHeight * (devicePixelRatio || 1);\n" +
+            "\tif (devicePixelRatio) c.scale(devicePixelRatio, devicePixelRatio);\n" +
+            "\tc.font = document.body.style.font;\n" +
+            "\n" +
+            "\tconst palette = [\n" +
+            "\t\t[0x50e150, 30, 30, 30],\n" +
+            "\t\t[0x50bebe, 30, 30, 30],\n" +
+            "\t\t[0xe17d00, 30, 30,  0],\n" +
+            "\t\t[0xc8c83c, 30, 30, 10],\n" +
+            "\t\t[0xe15a5a, 30, 40, 40],\n" +
+            "\t];\n" +
+            "\n" +
+            "\tfunction getColor(p) {\n" +
+            "\t\tconst v = Math.random();\n" +
+            "\t\treturn '#' + (p[0] + ((p[1] * v) << 16 | (p[2] * v) << 8 | (p[3] * v))).toString(16);\n" +
+            "\t}\n" +
+            "\n" +
+            "\tfunction f(level, left, width, type, title) {\n" +
+            "\t\tlevels[level].push({left: left, width: width, color: getColor(palette[type]), title: title});\n" +
+            "\t}\n" +
+            "\n" +
+            "\tfunction samples(n) {\n" +
+            "\t\treturn n === 1 ? '1 sample' : n.toString().replace(/\\B(?=(\\d{3})+(?!\\d))/g, ',') + ' samples';\n" +
+            "\t}\n" +
+            "\n" +
+            "\tfunction pct(a, b) {\n" +
+            "\t\treturn a >= b ? '100' : (100 * a / b).toFixed(2);\n" +
+            "\t}\n" +
+            "\n" +
+            "\tfunction findFrame(frames, x) {\n" +
+            "\t\tlet left = 0;\n" +
+            "\t\tlet right = frames.length - 1;\n" +
+            "\n" +
+            "\t\twhile (left <= right) {\n" +
+            "\t\t\tconst mid = (left + right) >>> 1;\n" +
+            "\t\t\tconst f = frames[mid];\n" +
+            "\n" +
+            "\t\t\tif (f.left > x) {\n" +
+            "\t\t\t\tright = mid - 1;\n" +
+            "\t\t\t} else if (f.left + f.width <= x) {\n" +
+            "\t\t\t\tleft = mid + 1;\n" +
+            "\t\t\t} else {\n" +
+            "\t\t\t\treturn f;\n" +
+            "\t\t\t}\n" +
+            "\t\t}\n" +
+            "\n" +
+            "\t\tif (frames[left] && (frames[left].left - x) * px < 0.5) return frames[left];\n" +
+            "\t\tif (frames[right] && (x - (frames[right].left + frames[right].width)) * px < 0.5) return frames[right];\n" +
+            "\n" +
+            "\t\treturn null;\n" +
+            "\t}\n" +
+            "\n" +
+            "\tfunction search(r) {\n" +
+            "\t\tif (r && (r = prompt('Enter regexp to search:', '')) === null) {\n" +
+            "\t\t\treturn;\n" +
+            "\t\t}\n" +
+            "\n" +
+            "\t\tpattern = r ? RegExp(r) : undefined;\n" +
+            "\t\tconst matched = render(root, rootLevel);\n" +
+            "\t\tdocument.getElementById('matchval').textContent = pct(matched, root.width) + '%';\n" +
+            "\t\tdocument.getElementById('match').style.display = r ? 'inherit' : 'none';\n" +
+            "\t}\n" +
+            "\n" +
+            "\tfunction render(newRoot, newLevel) {\n" +
+            "\t\tif (root) {\n" +
+            "\t\t\tc.fillStyle = '#ffffff';\n" +
+            "\t\t\tc.fillRect(0, 0, canvasWidth, canvasHeight);\n" +
+            "\t\t}\n" +
+            "\n" +
+            "\t\troot = newRoot || levels[0][0];\n" +
+            "\t\trootLevel = newLevel || 0;\n" +
+            "\t\tpx = canvasWidth / root.width;\n" +
+            "\n" +
+            "\t\tconst x0 = root.left;\n" +
+            "\t\tconst x1 = x0 + root.width;\n" +
+            "\t\tconst marked = [];\n" +
+            "\n" +
+            "\t\tfunction mark(f) {\n" +
+            "\t\t\treturn marked[f.left] >= f.width || (marked[f.left] = f.width);\n" +
+            "\t\t}\n" +
+            "\n" +
+            "\t\tfunction totalMarked() {\n" +
+            "\t\t\tlet total = 0;\n" +
+            "\t\t\tlet left = 0;\n" +
+            "\t\t\tfor (let x in marked) {\n" +
+            "\t\t\t\tif (+x >= left) {\n" +
+            "\t\t\t\t\ttotal += marked[x];\n" +
+            "\t\t\t\t\tleft = +x + marked[x];\n" +
+            "\t\t\t\t}\n" +
+            "\t\t\t}\n" +
+            "\t\t\treturn total;\n" +
+            "\t\t}\n" +
+            "\n" +
+            "\t\tfunction drawFrame(f, y, alpha) {\n" +
+            "\t\t\tif (f.left < x1 && f.left + f.width > x0) {\n" +
+            "\t\t\t\tc.fillStyle = pattern && f.title.match(pattern) && mark(f) ? '#ee00ee' : f.color;\n" +
+            "\t\t\t\tc.fillRect((f.left - x0) * px, y, f.width * px, 15);\n" +
+            "\n" +
+            "\t\t\t\tif (f.width * px >= 21) {\n" +
+            "\t\t\t\t\tconst chars = Math.floor(f.width * px / 7);\n" +
+            "\t\t\t\t\tconst title = f.title.length <= chars ? f.title : f.title.substring(0, chars - 2) + '..';\n" +
+            "\t\t\t\t\tc.fillStyle = '#000000';\n" +
+            "\t\t\t\t\tc.fillText(title, Math.max(f.left - x0, 0) * px + 3, y + 12, f.width * px - 6);\n" +
+            "\t\t\t\t}\n" +
+            "\n" +
+            "\t\t\t\tif (alpha) {\n" +
+            "\t\t\t\t\tc.fillStyle = 'rgba(255, 255, 255, 0.5)';\n" +
+            "\t\t\t\t\tc.fillRect((f.left - x0) * px, y, f.width * px, 15);\n" +
+            "\t\t\t\t}\n" +
+            "\t\t\t}\n" +
+            "\t\t}\n" +
+            "\n" +
+            "\t\tfor (let h = 0; h < levels.length; h++) {\n" +
+            "\t\t\tconst y = reverse ? h * 16 : canvasHeight - (h + 1) * 16;\n" +
+            "\t\t\tconst frames = levels[h];\n" +
+            "\t\t\tfor (let i = 0; i < frames.length; i++) {\n" +
+            "\t\t\t\tdrawFrame(frames[i], y, h < rootLevel);\n" +
+            "\t\t\t}\n" +
+            "\t\t}\n" +
+            "\n" +
+            "\t\treturn totalMarked();\n" +
+            "\t}\n" +
+            "\n" +
+            "\tcanvas.onmousemove = function() {\n" +
+            "\t\tconst h = Math.floor((reverse ? event.offsetY : (canvasHeight - event.offsetY)) / 16);\n" +
+            "\t\tif (h >= 0 && h < levels.length) {\n" +
+            "\t\t\tconst f = findFrame(levels[h], event.offsetX / px + root.left);\n" +
+            "\t\t\tif (f) {\n" +
+            "\t\t\t\thl.style.left = (Math.max(f.left - root.left, 0) * px + canvas.offsetLeft) + 'px';\n" +
+            "\t\t\t\thl.style.width = (Math.min(f.width, root.width) * px) + 'px';\n" +
+            "\t\t\t\thl.style.top = ((reverse ? h * 16 : canvasHeight - (h + 1) * 16) + canvas.offsetTop) + 'px';\n" +
+            "\t\t\t\thl.firstChild.textContent = f.title;\n" +
+            "\t\t\t\thl.style.display = 'block';\n" +
+            "\t\t\t\tcanvas.title = f.title + '\\n(' + samples(f.width) + ', ' + pct(f.width, levels[0][0].width) + '%)';\n" +
+            "\t\t\t\tcanvas.style.cursor = 'pointer';\n" +
+            "\t\t\t\tcanvas.onclick = function() {\n" +
+            "\t\t\t\t\tif (f != root) {\n" +
+            "\t\t\t\t\t\trender(f, h);\n" +
+            "\t\t\t\t\t\tcanvas.onmousemove();\n" +
+            "\t\t\t\t\t}\n" +
+            "\t\t\t\t};\n" +
+            "\t\t\t\tstatus.textContent = 'Function: ' + canvas.title;\n" +
+            "\t\t\t\treturn;\n" +
+            "\t\t\t}\n" +
+            "\t\t}\n" +
+            "\t\tcanvas.onmouseout();\n" +
+            "\t}\n" +
+            "\n" +
+            "\tcanvas.onmouseout = function() {\n" +
+            "\t\thl.style.display = 'none';\n" +
+            "\t\tstatus.textContent = '\\xa0';\n" +
+            "\t\tcanvas.title = '';\n" +
+            "\t\tcanvas.style.cursor = '';\n" +
+            "\t\tcanvas.onclick = '';\n" +
+            "\t}\n" +
+            "\n" +
+            "\tdocument.getElementById('reverse').onclick = function() {\n" +
+            "\t\treverse = !reverse;\n" +
+            "\t\trender();\n" +
+            "\t}\n" +
+            "\n" +
+            "\tdocument.getElementById('search').onclick = function() {\n" +
+            "\t\tsearch(true);\n" +
+            "\t}\n" +
+            "\n" +
+            "\tdocument.getElementById('reset').onclick = function() {\n" +
+            "\t\tsearch(false);\n" +
+            "\t}\n" +
+            "\n" +
+            "\twindow.onkeydown = function() {\n" +
+            "\t\tif (event.ctrlKey && event.keyCode === 70) {\n" +
+            "\t\t\tevent.preventDefault();\n" +
+            "\t\t\tsearch(true);\n" +
+            "\t\t} else if (event.keyCode === 27) {\n" +
+            "\t\t\tsearch(false);\n" +
+            "\t\t}\n" +
+            "\t}\n";
+
+    private static final String FOOTER = "render();\n" +
+            "</script></body></html>\n";
+}

src/converter/MANIFEST.MF

@@ -0,0 +1 @@
+Main-Class: Main

src/converter/Main.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Main entry point of jar.
+ * Lists available converters.
+ */
+public class Main {
+
+    public static void main(String[] args) {
+        System.out.println("Usage: java -cp converter.jar <Converter> [options] <input> <output>");
+        System.out.println();
+        System.out.println("Available converters:");
+        System.out.println("  FlameGraph input.collapsed output.html");
+        System.out.println("  jfr2flame  input.jfr       output.html");
+        System.out.println("  jfr2nflx   input.jfr       output.nflx");
+    }
+}

src/converter/jfr2flame.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import one.jfr.ClassRef;
+import one.jfr.Dictionary;
+import one.jfr.JfrReader;
+import one.jfr.MethodRef;
+import one.jfr.StackTrace;
+
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Converts .jfr output produced by async-profiler to HTML Flame Graph.
+ */
+public class jfr2flame {
+
+    private static final int FRAME_KERNEL = 5;
+
+    private final JfrReader jfr;
+    private final Dictionary<String> methodNames = new Dictionary<>();
+
+    public jfr2flame(JfrReader jfr) {
+        this.jfr = jfr;
+    }
+
+    public void convert(final FlameGraph fg) {
+        // Don't use lambda for faster startup
+        jfr.stackTraces.forEach(new Dictionary.Visitor<StackTrace>() {
+            @Override
+            public void visit(long id, StackTrace stackTrace) {
+                long[] methods = stackTrace.methods;
+                byte[] types = stackTrace.types;
+                String[] trace = new String[methods.length];
+                for (int i = 0; i < methods.length; i++) {
+                    trace[trace.length - 1 - i] = getMethodName(methods[i], types[i]);
+                }
+                fg.addSample(trace, stackTrace.samples);
+            }
+        });
+    }
+
+    private String getMethodName(long methodId, int type) {
+        String result = methodNames.get(methodId);
+        if (result != null) {
+            return result;
+        }
+
+        MethodRef method = jfr.methods.get(methodId);
+        ClassRef cls = jfr.classes.get(method.cls);
+        byte[] className = jfr.symbols.get(cls.name);
+        byte[] methodName = jfr.symbols.get(method.name);
+
+        if (className == null || className.length == 0) {
+            String methodStr = new String(methodName, StandardCharsets.UTF_8);
+            result = type == FRAME_KERNEL ? methodStr + "_[k]" : methodStr;
+        } else {
+            String classStr = new String(className, StandardCharsets.UTF_8);
+            String methodStr = new String(methodName, StandardCharsets.UTF_8);
+            result = classStr + '.' + methodStr + "_[j]";
+        }
+
+        methodNames.put(methodId, result);
+        return result;
+    }
+
+    public static void main(String[] args) throws Exception {
+        FlameGraph fg = new FlameGraph(args);
+        if (fg.input == null) {
+            System.out.println("Usage: java " + jfr2flame.class.getName() + " [options] input.jfr [output.html]");
+            System.exit(1);
+        }
+
+        try (JfrReader jfr = new JfrReader(fg.input)) {
+            new jfr2flame(jfr).convert(fg);
+        }
+
+        fg.dump();
+    }
+}

src/converter/jfr2nflx.java

@@ -0,0 +1,161 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import one.jfr.ClassRef;
+import one.jfr.Dictionary;
+import one.jfr.JfrReader;
+import one.jfr.MethodRef;
+import one.jfr.Sample;
+import one.jfr.StackTrace;
+import one.proto.Proto;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.Arrays;
+
+/**
+ * Converts .jfr output produced by async-profiler to nflxprofile format
+ * as described in https://github.com/Netflix/nflxprofile/blob/master/nflxprofile.proto.
+ * The result nflxprofile can be opened and analyzed with FlameScope.
+ */
+public class jfr2nflx {
+
+    private static final String[] FRAME_TYPE = {"jit", "jit", "inlined", "user", "user", "kernel"};
+    private static final byte[] NO_STACK = "[no_stack]".getBytes();
+
+    private final JfrReader jfr;
+
+    public jfr2nflx(JfrReader jfr) {
+        this.jfr = jfr;
+    }
+
+    public void dump(OutputStream out) throws IOException {
+        long startTime = System.nanoTime();
+
+        int samples = jfr.samples.size();
+        long durationTicks = samples == 0 ? 0 : jfr.samples.get(samples - 1).time - jfr.startTicks + 1;
+
+        final Proto profile = new Proto(200000)
+                .field(1, 0.0)
+                .field(2, Math.max(jfr.durationNanos / 1e9, durationTicks / (double) jfr.ticksPerSec))
+                .field(3, packSamples())
+                .field(4, packDeltas())
+                .field(6, "async-profiler")
+                .field(8, new Proto(32).field(1, "has_node_stack").field(2, "true"))
+                .field(8, new Proto(32).field(1, "has_samples_tid").field(2, "true"))
+                .field(11, packTids());
+
+        final Proto nodes = new Proto(10000);
+        final Proto node = new Proto(10000);
+
+        // Don't use lambda for faster startup
+        jfr.stackTraces.forEach(new Dictionary.Visitor<StackTrace>() {
+            @Override
+            public void visit(long id, StackTrace stackTrace) {
+                profile.field(5, nodes
+                        .field(1, (int) id)
+                        .field(2, packNode(node, stackTrace)));
+                nodes.reset();
+                node.reset();
+            }
+        });
+
+        out.write(profile.buffer(), 0, profile.size());
+
+        long endTime = System.nanoTime();
+        System.out.println("Wrote " + profile.size() + " bytes in " + (endTime - startTime) / 1e9 + " s");
+    }
+
+    private Proto packNode(Proto node, StackTrace stackTrace) {
+        long[] methods = stackTrace.methods;
+        byte[] types = stackTrace.types;
+        int top = methods.length - 1;
+
+        node.field(1, top >= 0 ? getMethodName(methods[top]) : NO_STACK);
+        node.field(2, 1);
+        node.field(4, top >= 0 ? FRAME_TYPE[types[top]] : "user");
+
+        for (Proto frame = new Proto(100); --top >= 0; frame.reset()) {
+            node.field(10, frame
+                    .field(1, getMethodName(methods[top]))
+                    .field(2, FRAME_TYPE[types[top]]));
+        }
+
+        return node;
+    }
+
+    private Proto packSamples() {
+        Proto proto = new Proto(10000);
+        for (Sample sample : jfr.samples) {
+            proto.writeInt(sample.stackTraceId);
+        }
+        return proto;
+    }
+
+    private Proto packDeltas() {
+        Proto proto = new Proto(10000);
+        double ticksPerSec = jfr.ticksPerSec;
+        long prevTime = jfr.startTicks;
+        for (Sample sample : jfr.samples) {
+            proto.writeDouble((sample.time - prevTime) / ticksPerSec);
+            prevTime = sample.time;
+        }
+        return proto;
+    }
+
+    private Proto packTids() {
+        Proto proto = new Proto(10000);
+        for (Sample sample : jfr.samples) {
+            proto.writeInt(sample.tid);
+        }
+        return proto;
+    }
+
+    private byte[] getMethodName(long methodId) {
+        MethodRef method = jfr.methods.get(methodId);
+        ClassRef cls = jfr.classes.get(method.cls);
+        byte[] className = jfr.symbols.get(cls.name);
+        byte[] methodName = jfr.symbols.get(method.name);
+
+        if (className == null || className.length == 0) {
+            return methodName;
+        } else {
+            byte[] fullName = Arrays.copyOf(className, className.length + 1 + methodName.length);
+            fullName[className.length] = '.';
+            System.arraycopy(methodName, 0, fullName, className.length + 1, methodName.length);
+            return fullName;
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        if (args.length < 2) {
+            System.out.println("Usage: java " + jfr2nflx.class.getName() + " input.jfr output.nflx");
+            System.exit(1);
+        }
+
+        File dst = new File(args[1]);
+        if (dst.isDirectory()) {
+            dst = new File(dst, new File(args[0]).getName().replace(".jfr", ".nflx"));
+        }
+
+        try (JfrReader jfr = new JfrReader(args[0]);
+             FileOutputStream out = new FileOutputStream(dst)) {
+            new jfr2nflx(jfr).dump(out);
+        }
+    }
+}

src/converter/one/jfr/ClassRef.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.jfr;
+
+public class ClassRef {
+    public final long name;
+
+    public ClassRef(long name) {
+        this.name = name;
+    }
+}

src/converter/one/jfr/Dictionary.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.jfr;
+
+/**
+ * Fast and compact long->Object map.
+ */
+public class Dictionary<T> {
+    private static final int INITIAL_CAPACITY = 16;
+
+    private long[] keys;
+    private Object[] values;
+    private int size;
+
+    public Dictionary() {
+        this.keys = new long[INITIAL_CAPACITY];
+        this.values = new Object[INITIAL_CAPACITY];
+    }
+
+    public void put(long key, T value) {
+        if (key == 0) {
+            throw new IllegalArgumentException("Zero key not allowed");
+        }
+
+        if (++size * 2 > keys.length) {
+            resize(keys.length * 2);
+        }
+
+        int mask = keys.length - 1;
+        int i = hashCode(key) & mask;
+        while (keys[i] != 0 && keys[i] != key) {
+            i = (i + 1) & mask;
+        }
+        keys[i] = key;
+        values[i] = value;
+    }
+
+    @SuppressWarnings("unchecked")
+    public T get(long key) {
+        int mask = keys.length - 1;
+        int i = hashCode(key) & mask;
+        while (keys[i] != key && keys[i] != 0) {
+            i = (i + 1) & mask;
+        }
+        return (T) values[i];
+    }
+
+    @SuppressWarnings("unchecked")
+    public void forEach(Visitor<T> visitor) {
+        for (int i = 0; i < keys.length; i++) {
+            if (keys[i] != 0) {
+                visitor.visit(keys[i], (T) values[i]);
+            }
+        }
+    }
+
+    public int preallocate(int count) {
+        int newSize = size + count;
+        if (newSize * 2 > keys.length) {
+            resize(Integer.highestOneBit(newSize * 4 - 1));
+        }
+        return count;
+    }
+
+    private void resize(int newCapacity) {
+        long[] newKeys = new long[newCapacity];
+        Object[] newValues = new Object[newCapacity];
+        int mask = newKeys.length - 1;
+
+        for (int i = 0; i < keys.length; i++) {
+            if (keys[i] != 0) {
+                for (int j = hashCode(keys[i]) & mask; ; j = (j + 1) & mask) {
+                    if (newKeys[j] == 0) {
+                        newKeys[j] = keys[i];
+                        newValues[j] = values[i];
+                        break;
+                    }
+                }
+            }
+        }
+
+        keys = newKeys;
+        values = newValues;
+    }
+
+    private static int hashCode(long key) {
+        return (int) (key ^ (key >>> 32));
+    }
+
+    public interface Visitor<T> {
+        void visit(long key, T value);
+    }
+}

src/converter/one/jfr/Element.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.jfr;
+
+class Element {
+
+    void addChild(Element e) {
+    }
+}

src/converter/one/jfr/JfrClass.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.jfr;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+class JfrClass extends Element {
+    final int id;
+    final String name;
+    final List<JfrField> fields;
+
+    JfrClass(Map<String, String> attributes) {
+        this.id = Integer.parseInt(attributes.get("id"));
+        this.name = attributes.get("name");
+        this.fields = new ArrayList<>(2);
+    }
+
+    @Override
+    void addChild(Element e) {
+        if (e instanceof JfrField) {
+            fields.add((JfrField) e);
+        }
+    }
+
+    JfrField field(String name) {
+        for (JfrField field : fields) {
+            if (field.name.equals(name)) {
+                return field;
+            }
+        }
+        return null;
+    }
+}

src/converter/one/jfr/JfrField.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.jfr;
+
+import java.util.Map;
+
+class JfrField extends Element {
+    final String name;
+    final int type;
+    final boolean constantPool;
+
+    JfrField(Map<String, String> attributes) {
+        this.name = attributes.get("name");
+        this.type = Integer.parseInt(attributes.get("class"));
+        this.constantPool = "true".equals(attributes.get("constantPool"));
+    }
+}

src/converter/one/jfr/JfrReader.java

@@ -0,0 +1,384 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.jfr;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Parses JFR output produced by async-profiler.
+ */
+public class JfrReader implements Closeable {
+    private static final int CHUNK_HEADER_SIZE = 68;
+    private static final int CPOOL_OFFSET = 16;
+    private static final int META_OFFSET = 24;
+
+    private final FileChannel ch;
+    private final ByteBuffer buf;
+
+    public final long startNanos;
+    public final long durationNanos;
+    public final long startTicks;
+    public final long ticksPerSec;
+
+    public final Dictionary<JfrClass> types = new Dictionary<>();
+    public final Map<String, JfrClass> typesByName = new HashMap<>();
+    public final Dictionary<String> threads = new Dictionary<>();
+    public final Dictionary<ClassRef> classes = new Dictionary<>();
+    public final Dictionary<byte[]> symbols = new Dictionary<>();
+    public final Dictionary<MethodRef> methods = new Dictionary<>();
+    public final Dictionary<StackTrace> stackTraces = new Dictionary<>();
+    public final Map<Integer, String> frameTypes = new HashMap<>();
+    public final Map<Integer, String> threadStates = new HashMap<>();
+    public final List<Sample> samples = new ArrayList<>();
+
+    public JfrReader(String fileName) throws IOException {
+        this.ch = FileChannel.open(Paths.get(fileName), StandardOpenOption.READ);
+        this.buf = ch.map(FileChannel.MapMode.READ_ONLY, 0, ch.size());
+
+        if (buf.getInt(0) != 0x464c5200) {
+            throw new IOException("Not a valid JFR file");
+        }
+
+        int version = buf.getInt(4);
+        if (version < 0x20000 || version > 0x2ffff) {
+            throw new IOException("Unsupported JFR version: " + (version >>> 16) + "." + (version & 0xffff));
+        }
+
+        this.startNanos = buf.getLong(32);
+        this.durationNanos = buf.getLong(40);
+        this.startTicks = buf.getLong(48);
+        this.ticksPerSec = buf.getLong(56);
+
+        readMeta();
+        readConstantPool();
+        readEvents();
+    }
+
+    @Override
+    public void close() throws IOException {
+        ch.close();
+    }
+
+    private void readMeta() {
+        buf.position(buf.getInt(META_OFFSET + 4));
+        getVarint();
+        getVarint();
+        getVarlong();
+        getVarlong();
+        getVarlong();
+
+        String[] strings = new String[getVarint()];
+        for (int i = 0; i < strings.length; i++) {
+            strings[i] = getString();
+        }
+        readElement(strings);
+    }
+
+    private Element readElement(String[] strings) {
+        String name = strings[getVarint()];
+
+        int attributeCount = getVarint();
+        Map<String, String> attributes = new HashMap<>(attributeCount);
+        for (int i = 0; i < attributeCount; i++) {
+            attributes.put(strings[getVarint()], strings[getVarint()]);
+        }
+
+        Element e = createElement(name, attributes);
+        int childCount = getVarint();
+        for (int i = 0; i < childCount; i++) {
+            e.addChild(readElement(strings));
+        }
+        return e;
+    }
+
+    private Element createElement(String name, Map<String, String> attributes) {
+        switch (name) {
+            case "class": {
+                JfrClass type = new JfrClass(attributes);
+                if (!attributes.containsKey("superType")) {
+                    types.put(type.id, type);
+                }
+                typesByName.put(type.name, type);
+                return type;
+            }
+            case "field":
+                return new JfrField(attributes);
+            default:
+                return new Element();
+        }
+    }
+
+    private void readConstantPool() {
+        int offset = buf.getInt(CPOOL_OFFSET + 4);
+        while (true) {
+            buf.position(offset);
+            getVarint();
+            getVarint();
+            getVarlong();
+            getVarlong();
+            long delta = getVarlong();
+            getVarint();
+
+            int poolCount = getVarint();
+            for (int i = 0; i < poolCount; i++) {
+                int type = getVarint();
+                readConstants(types.get(type));
+            }
+
+            if (delta == 0) {
+                break;
+            }
+            offset += delta;
+        }
+    }
+
+    private void readConstants(JfrClass type) {
+        switch (type.name) {
+            case "jdk.types.ChunkHeader":
+                buf.position(buf.position() + (CHUNK_HEADER_SIZE + 3));
+                break;
+            case "java.lang.Thread":
+                readThreads(type.field("group") != null);
+                break;
+            case "java.lang.Class":
+                readClasses(type.field("hidden") != null);
+                break;
+            case "jdk.types.Symbol":
+                readSymbols();
+                break;
+            case "jdk.types.Method":
+                readMethods();
+                break;
+            case "jdk.types.StackTrace":
+                readStackTraces();
+                break;
+            case "jdk.types.FrameType":
+                readMap(frameTypes);
+                break;
+            case "jdk.types.ThreadState":
+                readMap(threadStates);
+                break;
+            default:
+                readOtherConstants(type.fields);
+        }
+    }
+
+    private void readThreads(boolean hasGroup) {
+        int count = threads.preallocate(getVarint());
+        for (int i = 0; i < count; i++) {
+            long id = getVarlong();
+            String osName = getString();
+            int osThreadId = getVarint();
+            String javaName = getString();
+            long javaThreadId = getVarlong();
+            if (hasGroup) getVarlong();
+            threads.put(id, javaName != null ? javaName : osName);
+        }
+    }
+
+    private void readClasses(boolean hasHidden) {
+        int count = classes.preallocate(getVarint());
+        for (int i = 0; i < count; i++) {
+            long id = getVarlong();
+            long loader = getVarlong();
+            long name = getVarlong();
+            long pkg = getVarlong();
+            int modifiers = getVarint();
+            if (hasHidden) getVarint();
+            classes.put(id, new ClassRef(name));
+        }
+    }
+
+    private void readMethods() {
+        int count = methods.preallocate(getVarint());
+        for (int i = 0; i < count; i++) {
+            long id = getVarlong();
+            long cls = getVarlong();
+            long name = getVarlong();
+            long sig = getVarlong();
+            int modifiers = getVarint();
+            int hidden = getVarint();
+            methods.put(id, new MethodRef(cls, name, sig));
+        }
+    }
+
+    private void readStackTraces() {
+        int count = stackTraces.preallocate(getVarint());
+        for (int i = 0; i < count; i++) {
+            long id = getVarlong();
+            int truncated = getVarint();
+            StackTrace stackTrace = readStackTrace();
+            stackTraces.put(id, stackTrace);
+        }
+    }
+
+    private StackTrace readStackTrace() {
+        int depth = getVarint();
+        long[] methods = new long[depth];
+        byte[] types = new byte[depth];
+        for (int i = 0; i < depth; i++) {
+            methods[i] = getVarlong();
+            int line = getVarint();
+            int bci = getVarint();
+            types[i] = buf.get();
+        }
+        return new StackTrace(methods, types);
+    }
+
+    private void readSymbols() {
+        int count = symbols.preallocate(getVarint());
+        for (int i = 0; i < count; i++) {
+            long id = getVarlong();
+            if (buf.get() != 3) {
+                throw new IllegalArgumentException("Invalid symbol encoding");
+            }
+            symbols.put(id, getBytes());
+        }
+    }
+
+    private void readMap(Map<Integer, String> map) {
+        int count = getVarint();
+        for (int i = 0; i < count; i++) {
+            map.put(getVarint(), getString());
+        }
+    }
+
+    private void readOtherConstants(List<JfrField> fields) {
+        int stringType = getTypeId("java.lang.String");
+
+        boolean[] numeric = new boolean[fields.size()];
+        for (int i = 0; i < numeric.length; i++) {
+            JfrField f = fields.get(i);
+            numeric[i] = f.constantPool || f.type != stringType;
+        }
+
+        int count = getVarint();
+        for (int i = 0; i < count; i++) {
+            getVarlong();
+            readFields(numeric);
+        }
+    }
+
+    private void readFields(boolean[] numeric) {
+        for (boolean n : numeric) {
+            if (n) {
+                getVarlong();
+            } else {
+                getString();
+            }
+        }
+    }
+
+    private void readEvents() {
+        int executionSample = getTypeId("jdk.ExecutionSample");
+        int nativeMethodSample = getTypeId("jdk.NativeMethodSample");
+
+        buf.position(CHUNK_HEADER_SIZE);
+        while (buf.hasRemaining()) {
+            int position = buf.position();
+            int size = getVarint();
+            int type = getVarint();
+            if (type == executionSample || type == nativeMethodSample) {
+                readExecutionSample();
+            } else {
+                buf.position(position + size);
+            }
+        }
+
+        Collections.sort(samples);
+    }
+
+    private void readExecutionSample() {
+        long time = getVarlong();
+        int tid = getVarint();
+        int stackTraceId = getVarint();
+        int threadState = getVarint();
+        samples.add(new Sample(time, tid, stackTraceId, threadState));
+
+        StackTrace stackTrace = stackTraces.get(stackTraceId);
+        if (stackTrace != null) {
+            stackTrace.samples++;
+        }
+    }
+
+    private int getTypeId(String typeName) {
+        JfrClass type = typesByName.get(typeName);
+        return type != null ? type.id : -1;
+    }
+
+    private int getVarint() {
+        int result = 0;
+        for (int shift = 0; ; shift += 7) {
+            byte b = buf.get();
+            result |= (b & 0x7f) << shift;
+            if (b >= 0) {
+                return result;
+            }
+        }
+    }
+
+    private long getVarlong() {
+        long result = 0;
+        for (int shift = 0; shift < 56; shift += 7) {
+            byte b = buf.get();
+            result |= (b & 0x7fL) << shift;
+            if (b >= 0) {
+                return result;
+            }
+        }
+        return result | (buf.get() & 0xffL) << 56;
+    }
+
+    private String getString() {
+        switch (buf.get()) {
+            case 0:
+                return null;
+            case 1:
+                return "";
+            case 3:
+                return new String(getBytes(), StandardCharsets.UTF_8);
+            case 4: {
+                char[] chars = new char[getVarint()];
+                for (int i = 0; i < chars.length; i++) {
+                    chars[i] = (char) getVarint();
+                }
+                return new String(chars);
+            }
+            case 5:
+                return new String(getBytes(), StandardCharsets.ISO_8859_1);
+            default:
+                throw new IllegalArgumentException("Invalid string encoding");
+        }
+    }
+
+    private byte[] getBytes() {
+        byte[] bytes = new byte[getVarint()];
+        buf.get(bytes);
+        return bytes;
+    }
+}

src/converter/one/jfr/MethodRef.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.jfr;
+
+public class MethodRef {
+    public final long cls;
+    public final long name;
+    public final long sig;
+
+    public MethodRef(long cls, long name, long sig) {
+        this.cls = cls;
+        this.name = name;
+        this.sig = sig;
+    }
+}

src/converter/one/jfr/Sample.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.jfr;
+
+public class Sample implements Comparable<Sample> {
+    public final long time;
+    public final int tid;
+    public final int stackTraceId;
+    public final int threadState;
+
+    public Sample(long time, int tid, int stackTraceId, int threadState) {
+        this.time = time;
+        this.tid = tid;
+        this.stackTraceId = stackTraceId;
+        this.threadState = threadState;
+    }
+
+    @Override
+    public int compareTo(Sample o) {
+        return Long.compare(time, o.time);
+    }
+}

src/converter/one/jfr/StackTrace.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.jfr;
+
+public class StackTrace {
+    public final long[] methods;
+    public final byte[] types;
+    public long samples;
+
+    public StackTrace(long[] methods, byte[] types) {
+        this.methods = methods;
+        this.types = types;
+    }
+}

src/converter/one/proto/Proto.java

@@ -0,0 +1,127 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package one.proto;
+
+import java.util.Arrays;
+
+/**
+ * Simplified implementation of Protobuf writer, capable of encoding
+ * varints, doubles, ASCII strings and embedded messages
+ */
+public class Proto {
+    private byte[] buf;
+    private int pos;
+
+    public Proto(int capacity) {
+        this.buf = new byte[capacity];
+    }
+
+    public byte[] buffer() {
+        return buf;
+    }
+
+    public int size() {
+        return pos;
+    }
+
+    public void reset() {
+        pos = 0;
+    }
+
+    public Proto field(int index, int n) {
+        tag(index, 0);
+        writeInt(n);
+        return this;
+    }
+
+    public Proto field(int index, double d) {
+        tag(index, 1);
+        writeDouble(d);
+        return this;
+    }
+
+    public Proto field(int index, String s) {
+        tag(index, 2);
+        writeString(s);
+        return this;
+    }
+
+    public Proto field(int index, byte[] bytes) {
+        tag(index, 2);
+        writeBytes(bytes, 0, bytes.length);
+        return this;
+    }
+
+    public Proto field(int index, Proto proto) {
+        tag(index, 2);
+        writeBytes(proto.buf, 0, proto.pos);
+        return this;
+    }
+
+    public void writeInt(int n) {
+        int length = n == 0 ? 1 : (38 - Integer.numberOfLeadingZeros(n)) / 7;
+        ensureCapacity(length);
+
+        while (n > 0x7f) {
+            buf[pos++] = (byte) (0x80 | (n & 0x7f));
+            n >>>= 7;
+        }
+        buf[pos++] = (byte) n;
+    }
+
+    public void writeDouble(double d) {
+        ensureCapacity(8);
+        long n = Double.doubleToRawLongBits(d);
+        buf[pos] = (byte) n;
+        buf[pos + 1] = (byte) (n >>> 8);
+        buf[pos + 2] = (byte) (n >>> 16);
+        buf[pos + 3] = (byte) (n >>> 24);
+        buf[pos + 4] = (byte) (n >>> 32);
+        buf[pos + 5] = (byte) (n >>> 40);
+        buf[pos + 6] = (byte) (n >>> 48);
+        buf[pos + 7] = (byte) (n >>> 56);
+        pos += 8;
+    }
+
+    public void writeString(String s) {
+        int length = s.length();
+        writeInt(length);
+        ensureCapacity(length);
+
+        for (int i = 0; i < length; i++) {
+            buf[pos++] = (byte) s.charAt(i);
+        }
+    }
+
+    public void writeBytes(byte[] bytes, int offset, int length) {
+        writeInt(length);
+        ensureCapacity(length);
+        System.arraycopy(bytes, offset, buf, pos, length);
+        pos += length;
+    }
+
+    private void tag(int index, int type) {
+        ensureCapacity(1);
+        buf[pos++] = (byte) (index << 3 | type);
+    }
+
+    private void ensureCapacity(int length) {
+        if (pos + length > buf.length) {
+            buf = Arrays.copyOf(buf, Math.max(pos + length, buf.length * 2));
+        }
+    }
+}

src/dictionary.cpp

@@ -0,0 +1,126 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "dictionary.h"
+#include "arch.h"
+
+
+static inline char* allocateKey(const char* key, size_t length) {
+    char* result = (char*)malloc(length + 1);
+    memcpy(result, key, length);
+    result[length] = 0;
+    return result;
+}
+
+static inline bool keyEquals(const char* candidate, const char* key, size_t length) {
+    return strncmp(candidate, key, length) == 0 && candidate[length] == 0;
+}
+
+
+Dictionary::Dictionary() {
+    _table = (DictTable*)calloc(1, sizeof(DictTable));
+    _table->base_index = _base_index = 1;
+}
+
+Dictionary::~Dictionary() {
+    clear(_table);
+    free(_table);
+}
+
+void Dictionary::clear() {
+    clear(_table);
+    memset(_table, 0, sizeof(DictTable));
+    _table->base_index = _base_index = 1;
+}
+
+void Dictionary::clear(DictTable* table) {
+    for (int i = 0; i < ROWS; i++) {
+        DictRow* row = &table->rows[i];
+        for (int j = 0; j < CELLS; j++) {
+            free(row->keys[j]);
+        }
+        if (row->next != NULL) {
+            clear(row->next);
+            free(row->next);
+        }
+    }
+}
+
+// Many popular symbols are quite short, e.g. "[B", "()V" etc.
+// FNV-1a is reasonably fast and sufficiently random.
+unsigned int Dictionary::hash(const char* key, size_t length) {
+    unsigned int h = 2166136261U;
+    for (size_t i = 0; i < length; i++) {
+        h = (h ^ key[i]) * 16777619;
+    }
+    return h;
+}
+
+unsigned int Dictionary::lookup(const char* key) {
+    return lookup(key, strlen(key));
+}
+
+unsigned int Dictionary::lookup(const char* key, size_t length) {
+    DictTable* table = _table;
+    unsigned int h = hash(key, length);
+
+    while (true) {
+        DictRow* row = &table->rows[h % ROWS];
+        for (int c = 0; c < CELLS; c++) {
+            if (row->keys[c] == NULL) {
+                char* new_key = allocateKey(key, length);
+                if (__sync_bool_compare_and_swap(&row->keys[c], NULL, new_key)) {
+                    return table->index(h % ROWS, c);
+                }
+                free(new_key);
+            }
+            if (keyEquals(row->keys[c], key, length)) {
+                return table->index(h % ROWS, c);
+            }
+        }
+
+        if (row->next == NULL) {
+            DictTable* new_table = (DictTable*)calloc(1, sizeof(DictTable));
+            new_table->base_index = __sync_add_and_fetch(&_base_index, TABLE_CAPACITY);
+            if (!__sync_bool_compare_and_swap(&row->next, NULL, new_table)) {
+                free(new_table);
+            }
+        }
+
+        table = row->next;
+        h = (h >> ROW_BITS) | (h << (32 - ROW_BITS));
+    }
+}
+
+void Dictionary::collect(std::map<unsigned int, const char*>& map) {
+    collect(map, _table);
+}
+
+void Dictionary::collect(std::map<unsigned int, const char*>& map, DictTable* table) {
+    for (int i = 0; i < ROWS; i++) {
+        DictRow* row = &table->rows[i];
+        for (int j = 0; j < CELLS; j++) {
+            if (row->keys[j] != NULL) {
+                map[table->index(i, j)] = row->keys[j];
+            }
+        }
+        if (row->next != NULL) {
+            collect(map, row->next);
+        }
+    }
+}

src/dictionary.h

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _DICTIONARY_H
+#define _DICTIONARY_H
+
+#include <map>
+#include <stddef.h>
+
+
+#define ROW_BITS        7
+#define ROWS            (1 << ROW_BITS)
+#define CELLS           3
+#define TABLE_CAPACITY  (ROWS * CELLS)
+
+
+struct DictTable;
+
+struct DictRow {
+    char* keys[CELLS];
+    DictTable* next;
+};
+
+struct DictTable {
+    DictRow rows[ROWS];
+    unsigned int base_index;
+
+    unsigned int index(int row, int col) {
+        return base_index + (col << ROW_BITS) + row;
+    }
+};
+
+// Append-only concurrent hash table based on multi-level arrays
+class Dictionary {
+  private:
+    DictTable* _table;
+    volatile unsigned int _base_index;
+
+    static void clear(DictTable* table);
+
+    static unsigned int hash(const char* key, size_t length);
+
+    static void collect(std::map<unsigned int, const char*>& map, DictTable* table);
+
+  public:
+    Dictionary();
+    ~Dictionary();
+
+    void clear();
+
+    unsigned int lookup(const char* key);
+    unsigned int lookup(const char* key, size_t length);
+
+    void collect(std::map<unsigned int, const char*>& map);
+};
+
+#endif // _DICTIONARY_H

src/engine.cpp

@@ -18,26 +18,50 @@
 #include "stackFrame.h"
 
 
+volatile bool Engine::_enabled;
+
+Error Engine::check(Arguments& args) {
+    return Error::OK;
+}
+
+CStack Engine::cstack() {
+    return CSTACK_FP;
+}
+
 int Engine::getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                           const void* jit_min_address, const void* jit_max_address) {
-    StackFrame frame(ucontext);
-    const void* pc = (const void*)frame.pc();
-    uintptr_t fp = frame.fp();
+                           CodeCache* java_methods, CodeCache* runtime_stubs) {
+    const void* pc;
+    uintptr_t fp;
     uintptr_t prev_fp = (uintptr_t)&fp;
+    uintptr_t bottom = prev_fp + 0x100000;
+
+    if (ucontext == NULL) {
+        pc = __builtin_return_address(0);
+        fp = (uintptr_t)__builtin_frame_address(1);
+    } else {
+        StackFrame frame(ucontext);
+        pc = (const void*)frame.pc();
+        fp = frame.fp();
+    }
 
     int depth = 0;
-    const void* const valid_pc = (const void*)0x1000;
+    const void* const valid_pc = (const void* const)0x1000;
 
     // Walk until the bottom of the stack or until the first Java frame
     while (depth < max_depth && pc >= valid_pc) {
-        callchain[depth++] = pc;
-
-        if (pc >= jit_min_address && pc < jit_max_address) {
+        if (java_methods->contains(pc) || runtime_stubs->contains(pc)) {
             break;
         }
 
+        callchain[depth++] = pc;
+
         // Check if the next frame is below on the current stack
-        if (fp <= prev_fp || fp >= prev_fp + 0x40000) {
+        if (fp <= prev_fp || fp >= prev_fp + 0x40000 || fp >= bottom) {
+            break;
+        }
+
+        // Frame pointer must be word aligned
+        if ((fp & (sizeof(uintptr_t) - 1)) != 0) {
             break;
         }
 

src/engine.h

@@ -18,21 +18,50 @@
 #define _ENGINE_H
 
 #include "arguments.h"
+#include "codeCache.h"
 
 
 class Engine {
+  protected:
+    static volatile bool _enabled;
+
   public:
     virtual const char* name() = 0;
     virtual const char* units() = 0;
 
+    virtual Error check(Arguments& args);
     virtual Error start(Arguments& args) = 0;
     virtual void stop() = 0;
 
-    virtual void onThreadStart() {}
-    virtual void onThreadEnd() {}
-
+    virtual CStack cstack();
     virtual int getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                               const void* jit_min_address, const void* jit_max_address);
+                               CodeCache* java_methods, CodeCache* runtime_stubs);
+
+    void enableEvents(bool enabled) {
+        _enabled = enabled;
+    }
+};
+
+class NoopEngine : public Engine {
+  public:
+    const char* name() {
+        return "noop";
+    }
+
+    const char* units() {
+        return "ns";
+    }
+
+    Error start(Arguments& args) {
+        return Error::OK;
+    }
+
+    void stop() {
+    }
+
+    CStack cstack() {
+        return CSTACK_NO;
+    }
 };
 
 #endif // _ENGINE_H

src/event.h

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _EVENT_H
+#define _EVENT_H
+
+#include <stdint.h>
+#include "os.h"
+
+
+class Event {
+  public:
+    u32 id() {
+        return *(u32*)this;
+    }
+};
+
+class ExecutionEvent : public Event {
+  public:
+    ThreadState _thread_state;
+
+    ExecutionEvent() : _thread_state(THREAD_RUNNING) {
+    }
+};
+
+class AllocEvent : public Event {
+  public:
+    u32 _class_id;
+    u64 _total_size;
+    u64 _instance_size;
+};
+
+class LockEvent : public Event {
+  public:
+    u32 _class_id;
+    u64 _start_time;
+    u64 _end_time;
+    uintptr_t _address;
+    long long _timeout;
+};
+
+#endif // _EVENT_H

src/flameGraph.cpp

@@ -1,378 +1,254 @@
 /*
- * Copyright 2018 Andrei Pangin
+ * Copyright 2020 Andrei Pangin
  *
- * This is a specialized C++ port of the FlameGraph script available at
- * https://github.com/brendangregg/FlameGraph/blob/master/flamegraph.pl
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
  *
- * Copyright 2016 Netflix, Inc.
- * Copyright 2011 Joyent, Inc.  All rights reserved.
- * Copyright 2011 Brendan Gregg.  All rights reserved.
+ *     http://www.apache.org/licenses/LICENSE-2.0
  *
- * CDDL HEADER START
- *
- * The contents of this file are subject to the terms of the
- * Common Development and Distribution License (the "License").
- * You may not use this file except in compliance with the License.
- *
- * You can obtain a copy of the license at docs/cddl1.txt or
- * http://opensource.org/licenses/CDDL-1.0.
- * See the License for the specific language governing permissions
- * and limitations under the License.
- *
- * When distributing Covered Code, include this CDDL HEADER in each
- * file and include the License file at docs/cddl1.txt.
- * If applicable, add the following below this CDDL HEADER, with the
- * fields enclosed by brackets "[]" replaced with your own identifying
- * information: Portions Copyright [yyyy] [name of copyright owner]
- *
- * CDDL HEADER END
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
  */
 
-#include <iomanip>
-#include <vector>
 #include <algorithm>
-#include <math.h>
+#include <vector>
 #include <stdio.h>
-#include <stdlib.h>
 #include "flameGraph.h"
 
 
-static const char SVG_HEADER[] =
-    "<?xml version=\"1.0\" standalone=\"no\"?>\n"
-    "<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n"
-    "<svg version=\"1.1\" width=\"%d\" height=\"%d\" onload=\"init(evt)\" viewBox=\"0 0 %d %d\" xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\">\n"
-    "<style type=\"text/css\">\n"
-    "\ttext { font-family:Verdana; font-size:12px; fill:rgb(0,0,0); }\n"
-    "\t#search { opacity:0.1; cursor:pointer; }\n"
-    "\t#search:hover, #search.show { opacity:1; }\n"
-    "\t#subtitle { text-anchor:middle; font-color:rgb(160,160,160); }\n"
-    "\t#title { text-anchor:middle; font-size:17px}\n"
-    "\t#unzoom { cursor:pointer; }\n"
-    "\t#frames > *:hover { stroke:black; stroke-width:0.5; cursor:pointer; }\n"
-    "\t.hide { display:none; }\n"
-    "\t.parent { opacity:0.5; }\n"
+static const char FLAMEGRAPH_HEADER[] =
+    "<!DOCTYPE html>\n"
+    "<html lang='en'>\n"
+    "<head>\n"
+    "<meta charset='utf-8'>\n"
+    "<style>\n"
+    "\tbody {margin: 0; padding: 10px; background-color: #ffffff}\n"
+    "\th1 {margin: 5px 0 0 0; font-size: 18px; font-weight: normal; text-align: center}\n"
+    "\theader {margin: -24px 0 5px 0; line-height: 24px}\n"
+    "\tbutton {font: 12px sans-serif; cursor: pointer}\n"
+    "\tp {margin: 5px 0 5px 0}\n"
+    "\ta {color: #0366d6}\n"
+    "\t#hl {position: absolute; display: none; overflow: hidden; white-space: nowrap; pointer-events: none; background-color: #ffffe0; outline: 1px solid #ffc000; height: 15px}\n"
+    "\t#hl span {padding: 0 3px 0 3px}\n"
+    "\t#status {overflow: hidden; white-space: nowrap}\n"
+    "\t#match {overflow: hidden; white-space: nowrap; display: none; float: right; text-align: right}\n"
+    "\t#reset {cursor: pointer}\n"
     "</style>\n"
-    "<script type=\"text/ecmascript\">\n"
-    "<![CDATA[\n"
-    "\t\"use strict\";\n"
-    "\tvar details, searchbtn, unzoombtn, matchedtxt, svg, searching;\n"
-    "\tfunction init(evt) {\n"
-    "\t\tdetails = document.getElementById(\"details\").firstChild;\n"
-    "\t\tsearchbtn = document.getElementById(\"search\");\n"
-    "\t\tunzoombtn = document.getElementById(\"unzoom\");\n"
-    "\t\tmatchedtxt = document.getElementById(\"matched\");\n"
-    "\t\tsvg = document.getElementsByTagName(\"svg\")[0];\n"
-    "\t\tsearching = 0;\n"
+    "</head>\n"
+    "<body style='font: 12px Verdana, sans-serif'>\n"
+    "<h1>%s</h1>\n"
+    "<header style='text-align: left'><button id='reverse' title='Reverse'>&#x1f53b;</button>&nbsp;&nbsp;<button id='search' title='Search'>&#x1f50d;</button></header>\n"
+    "<header style='text-align: right'>Produced by <a href='https://github.com/jvm-profiling-tools/async-profiler'>async-profiler</a></header>\n"
+    "<canvas id='canvas' style='width: 100%%; height: %dpx'></canvas>\n"
+    "<div id='hl'><span></span></div>\n"
+    "<p id='match'>Matched: <span id='matchval'></span> <span id='reset' title='Clear'>&#x274c;</span></p>\n"
+    "<p id='status'>&nbsp;</p>\n"
+    "<script>\n"
+    "\t// Copyright 2020 Andrei Pangin\n"
+    "\t// Licensed under the Apache License, Version 2.0.\n"
+    "\t'use strict';\n"
+    "\tvar root, rootLevel, px, pattern;\n"
+    "\tvar reverse = %s;\n"
+    "\tconst levels = Array(%d);\n"
+    "\tfor (let h = 0; h < levels.length; h++) {\n"
+    "\t\tlevels[h] = [];\n"
     "\t}\n"
     "\n"
-    "\twindow.addEventListener(\"click\", function(e) {\n"
-    "\t\tvar target = find_group(e.target);\n"
-    "\t\tif (target) {\n"
-    "\t\t\tif (target.nodeName == \"a\") {\n"
-    "\t\t\t\tif (e.ctrlKey === false) return;\n"
-    "\t\t\t\te.preventDefault();\n"
+    "\tconst canvas = document.getElementById('canvas');\n"
+    "\tconst c = canvas.getContext('2d');\n"
+    "\tconst hl = document.getElementById('hl');\n"
+    "\tconst status = document.getElementById('status');\n"
+    "\n"
+    "\tconst canvasWidth = canvas.offsetWidth;\n"
+    "\tconst canvasHeight = canvas.offsetHeight;\n"
+    "\tcanvas.style.width = canvasWidth + 'px';\n"
+    "\tcanvas.width = canvasWidth * (devicePixelRatio || 1);\n"
+    "\tcanvas.height = canvasHeight * (devicePixelRatio || 1);\n"
+    "\tif (devicePixelRatio) c.scale(devicePixelRatio, devicePixelRatio);\n"
+    "\tc.font = document.body.style.font;\n"
+    "\n"
+    "\tconst palette = [\n"
+    "\t\t[0x50e150, 30, 30, 30],\n"
+    "\t\t[0x50bebe, 30, 30, 30],\n"
+    "\t\t[0xe17d00, 30, 30,  0],\n"
+    "\t\t[0xc8c83c, 30, 30, 10],\n"
+    "\t\t[0xe15a5a, 30, 40, 40],\n"
+    "\t];\n"
+    "\n"
+    "\tfunction getColor(p) {\n"
+    "\t\tconst v = Math.random();\n"
+    "\t\treturn '#' + (p[0] + ((p[1] * v) << 16 | (p[2] * v) << 8 | (p[3] * v))).toString(16);\n"
+    "\t}\n"
+    "\n"
+    "\tfunction f(level, left, width, type, title) {\n"
+    "\t\tlevels[level].push({left: left, width: width, color: getColor(palette[type]), title: title});\n"
+    "\t}\n"
+    "\n"
+    "\tfunction samples(n) {\n"
+    "\t\treturn n === 1 ? '1 sample' : n.toString().replace(/\\B(?=(\\d{3})+(?!\\d))/g, ',') + ' samples';\n"
+    "\t}\n"
+    "\n"
+    "\tfunction pct(a, b) {\n"
+    "\t\treturn a >= b ? '100' : (100 * a / b).toFixed(2);\n"
+    "\t}\n"
+    "\n"
+    "\tfunction findFrame(frames, x) {\n"
+    "\t\tlet left = 0;\n"
+    "\t\tlet right = frames.length - 1;\n"
+    "\n"
+    "\t\twhile (left <= right) {\n"
+    "\t\t\tconst mid = (left + right) >>> 1;\n"
+    "\t\t\tconst f = frames[mid];\n"
+    "\n"
+    "\t\t\tif (f.left > x) {\n"
+    "\t\t\t\tright = mid - 1;\n"
+    "\t\t\t} else if (f.left + f.width <= x) {\n"
+    "\t\t\t\tleft = mid + 1;\n"
+    "\t\t\t} else {\n"
+    "\t\t\t\treturn f;\n"
     "\t\t\t}\n"
-    "\t\t\tif (target.classList.contains(\"parent\")) unzoom();\n"
-    "\t\t\tzoom(target);\n"
     "\t\t}\n"
-    "\t\telse if (e.target.id == \"unzoom\") unzoom();\n"
-    "\t\telse if (e.target.id == \"search\") search_prompt();\n"
-    "\t}, false)\n"
     "\n"
-    "\t// mouse-over for info\n"
-    "\t// show\n"
-    "\twindow.addEventListener(\"mouseover\", function(e) {\n"
-    "\t\tvar target = find_group(e.target);\n"
-    "\t\tif (target) details.nodeValue = \"Function: \" + g_to_text(target);\n"
-    "\t}, false)\n"
+    "\t\tif (frames[left] && (frames[left].left - x) * px < 0.5) return frames[left];\n"
+    "\t\tif (frames[right] && (x - (frames[right].left + frames[right].width)) * px < 0.5) return frames[right];\n"
     "\n"
-    "\t// clear\n"
-    "\twindow.addEventListener(\"mouseout\", function(e) {\n"
-    "\t\tvar target = find_group(e.target);\n"
-    "\t\tif (target) details.nodeValue = ' ';\n"
-    "\t}, false)\n"
+    "\t\treturn null;\n"
+    "\t}\n"
     "\n"
-    "\t// ctrl-F for search\n"
-    "\twindow.addEventListener(\"keydown\",function (e) {\n"
-    "\t\tif (e.keyCode === 114 || (e.ctrlKey && e.keyCode === 70)) {\n"
-    "\t\t\te.preventDefault();\n"
-    "\t\t\tsearch_prompt();\n"
-    "\t\t}\n"
-    "\t}, false)\n"
-    "\n"
-    "\t// functions\n"
-    "\tfunction find_child(node, selector) {\n"
-    "\t\tvar children = node.querySelectorAll(selector);\n"
-    "\t\tif (children.length) return children[0];\n"
-    "\t\treturn;\n"
-    "\t}\n"
-    "\tfunction find_group(node) {\n"
-    "\t\tvar parent = node.parentElement;\n"
-    "\t\tif (!parent) return;\n"
-    "\t\tif (parent.id == \"frames\") return node;\n"
-    "\t\treturn find_group(parent);\n"
-    "\t}\n"
-    "\tfunction orig_save(e, attr, val) {\n"
-    "\t\tif (e.attributes[\"_orig_\" + attr] != undefined) return;\n"
-    "\t\tif (e.attributes[attr] == undefined) return;\n"
-    "\t\tif (val == undefined) val = e.attributes[attr].value;\n"
-    "\t\te.setAttribute(\"_orig_\" + attr, val);\n"
-    "\t}\n"
-    "\tfunction orig_load(e, attr) {\n"
-    "\t\tif (e.attributes[\"_orig_\"+attr] == undefined) return;\n"
-    "\t\te.attributes[attr].value = e.attributes[\"_orig_\" + attr].value;\n"
-    "\t\te.removeAttribute(\"_orig_\"+attr);\n"
-    "\t}\n"
-    "\tfunction g_to_text(e) {\n"
-    "\t\tvar text = find_child(e, \"title\").firstChild.nodeValue;\n"
-    "\t\treturn (text)\n"
-    "\t}\n"
-    "\tfunction g_to_func(e) {\n"
-    "\t\tvar func = g_to_text(e);\n"
-    "\t\t// if there's any manipulation we want to do to the function\n"
-    "\t\t// name before it's searched, do it here before returning.\n"
-    "\t\treturn (func);\n"
-    "\t}\n"
-    "\tfunction update_text(e) {\n"
-    "\t\tvar r = find_child(e, \"rect\");\n"
-    "\t\tvar t = find_child(e, \"text\");\n"
-    "\t\tvar w = parseFloat(r.attributes.width.value) -3;\n"
-    "\t\tvar txt = find_child(e, \"title\").textContent.replace(/\\([^(]*\\)$/,\"\");\n"
-    "\t\tt.attributes.x.value = parseFloat(r.attributes.x.value) + 3;\n"
-    "\n"
-    "\t\t// Smaller than this size won't fit anything\n"
-    "\t\tif (w < 2 * 12 * 0.59) {\n"
-    "\t\t\tt.textContent = \"\";\n"
+    "\tfunction search(r) {\n"
+    "\t\tif (r && (r = prompt('Enter regexp to search:', '')) === null) {\n"
     "\t\t\treturn;\n"
     "\t\t}\n"
     "\n"
-    "\t\tt.textContent = txt;\n"
-    "\t\t// Fit in full text width\n"
-    "\t\tif (/^ *$/.test(txt) || t.getSubStringLength(0, txt.length) < w)\n"
-    "\t\t\treturn;\n"
+    "\t\tpattern = r ? RegExp(r) : undefined;\n"
+    "\t\tconst matched = render(root, rootLevel);\n"
+    "\t\tdocument.getElementById('matchval').textContent = pct(matched, root.width) + '%%';\n"
+    "\t\tdocument.getElementById('match').style.display = r ? 'inherit' : 'none';\n"
+    "\t}\n"
     "\n"
-    "\t\tfor (var x = txt.length - 2; x > 0; x--) {\n"
-    "\t\t\tif (t.getSubStringLength(0, x + 2) <= w) {\n"
-    "\t\t\t\tt.textContent = txt.substring(0, x) + \"..\";\n"
+    "\tfunction render(newRoot, newLevel) {\n"
+    "\t\tif (root) {\n"
+    "\t\t\tc.fillStyle = '#ffffff';\n"
+    "\t\t\tc.fillRect(0, 0, canvasWidth, canvasHeight);\n"
+    "\t\t}\n"
+    "\n"
+    "\t\troot = newRoot || levels[0][0];\n"
+    "\t\trootLevel = newLevel || 0;\n"
+    "\t\tpx = canvasWidth / root.width;\n"
+    "\n"
+    "\t\tconst x0 = root.left;\n"
+    "\t\tconst x1 = x0 + root.width;\n"
+    "\t\tconst marked = [];\n"
+    "\n"
+    "\t\tfunction mark(f) {\n"
+    "\t\t\treturn marked[f.left] >= f.width || (marked[f.left] = f.width);\n"
+    "\t\t}\n"
+    "\n"
+    "\t\tfunction totalMarked() {\n"
+    "\t\t\tlet total = 0;\n"
+    "\t\t\tlet left = 0;\n"
+    "\t\t\tfor (let x in marked) {\n"
+    "\t\t\t\tif (+x >= left) {\n"
+    "\t\t\t\t\ttotal += marked[x];\n"
+    "\t\t\t\t\tleft = +x + marked[x];\n"
+    "\t\t\t\t}\n"
+    "\t\t\t}\n"
+    "\t\t\treturn total;\n"
+    "\t\t}\n"
+    "\n"
+    "\t\tfunction drawFrame(f, y, alpha) {\n"
+    "\t\t\tif (f.left < x1 && f.left + f.width > x0) {\n"
+    "\t\t\t\tc.fillStyle = pattern && f.title.match(pattern) && mark(f) ? '#ee00ee' : f.color;\n"
+    "\t\t\t\tc.fillRect((f.left - x0) * px, y, f.width * px, 15);\n"
+    "\n"
+    "\t\t\t\tif (f.width * px >= 21) {\n"
+    "\t\t\t\t\tconst chars = Math.floor(f.width * px / 7);\n"
+    "\t\t\t\t\tconst title = f.title.length <= chars ? f.title : f.title.substring(0, chars - 2) + '..';\n"
+    "\t\t\t\t\tc.fillStyle = '#000000';\n"
+    "\t\t\t\t\tc.fillText(title, Math.max(f.left - x0, 0) * px + 3, y + 12, f.width * px - 6);\n"
+    "\t\t\t\t}\n"
+    "\n"
+    "\t\t\t\tif (alpha) {\n"
+    "\t\t\t\t\tc.fillStyle = 'rgba(255, 255, 255, 0.5)';\n"
+    "\t\t\t\t\tc.fillRect((f.left - x0) * px, y, f.width * px, 15);\n"
+    "\t\t\t\t}\n"
+    "\t\t\t}\n"
+    "\t\t}\n"
+    "\n"
+    "\t\tfor (let h = 0; h < levels.length; h++) {\n"
+    "\t\t\tconst y = reverse ? h * 16 : canvasHeight - (h + 1) * 16;\n"
+    "\t\t\tconst frames = levels[h];\n"
+    "\t\t\tfor (let i = 0; i < frames.length; i++) {\n"
+    "\t\t\t\tdrawFrame(frames[i], y, h < rootLevel);\n"
+    "\t\t\t}\n"
+    "\t\t}\n"
+    "\n"
+    "\t\treturn totalMarked();\n"
+    "\t}\n"
+    "\n"
+    "\tcanvas.onmousemove = function() {\n"
+    "\t\tconst h = Math.floor((reverse ? event.offsetY : (canvasHeight - event.offsetY)) / 16);\n"
+    "\t\tif (h >= 0 && h < levels.length) {\n"
+    "\t\t\tconst f = findFrame(levels[h], event.offsetX / px + root.left);\n"
+    "\t\t\tif (f) {\n"
+    "\t\t\t\thl.style.left = (Math.max(f.left - root.left, 0) * px + canvas.offsetLeft) + 'px';\n"
+    "\t\t\t\thl.style.width = (Math.min(f.width, root.width) * px) + 'px';\n"
+    "\t\t\t\thl.style.top = ((reverse ? h * 16 : canvasHeight - (h + 1) * 16) + canvas.offsetTop) + 'px';\n"
+    "\t\t\t\thl.firstChild.textContent = f.title;\n"
+    "\t\t\t\thl.style.display = 'block';\n"
+    "\t\t\t\tcanvas.title = f.title + '\\n(' + samples(f.width) + ', ' + pct(f.width, levels[0][0].width) + '%%)';\n"
+    "\t\t\t\tcanvas.style.cursor = 'pointer';\n"
+    "\t\t\t\tcanvas.onclick = function() {\n"
+    "\t\t\t\t\tif (f != root) {\n"
+    "\t\t\t\t\t\trender(f, h);\n"
+    "\t\t\t\t\t\tcanvas.onmousemove();\n"
+    "\t\t\t\t\t}\n"
+    "\t\t\t\t};\n"
+    "\t\t\t\tstatus.textContent = 'Function: ' + canvas.title;\n"
     "\t\t\t\treturn;\n"
     "\t\t\t}\n"
     "\t\t}\n"
-    "\t\tt.textContent = \"\";\n"
+    "\t\tcanvas.onmouseout();\n"
     "\t}\n"
     "\n"
-    "\t// zoom\n"
-    "\tfunction zoom_reset(e) {\n"
-    "\t\tif (e.attributes != undefined) {\n"
-    "\t\t\torig_load(e, \"x\");\n"
-    "\t\t\torig_load(e, \"width\");\n"
-    "\t\t}\n"
-    "\t\tif (e.childNodes == undefined) return;\n"
-    "\t\tfor (var i = 0, c = e.childNodes; i < c.length; i++) {\n"
-    "\t\t\tzoom_reset(c[i]);\n"
-    "\t\t}\n"
-    "\t}\n"
-    "\tfunction zoom_child(e, x, ratio) {\n"
-    "\t\tif (e.attributes != undefined) {\n"
-    "\t\t\tif (e.attributes.x != undefined) {\n"
-    "\t\t\t\torig_save(e, \"x\");\n"
-    "\t\t\t\te.attributes.x.value = (parseFloat(e.attributes.x.value) - x - 10) * ratio + 10;\n"
-    "\t\t\t\tif (e.tagName == \"text\")\n"
-    "\t\t\t\t\te.attributes.x.value = find_child(e.parentNode, \"rect[x]\").attributes.x.value + 3;\n"
-    "\t\t\t}\n"
-    "\t\t\tif (e.attributes.width != undefined) {\n"
-    "\t\t\t\torig_save(e, \"width\");\n"
-    "\t\t\t\te.attributes.width.value = parseFloat(e.attributes.width.value) * ratio;\n"
-    "\t\t\t}\n"
-    "\t\t}\n"
-    "\n"
-    "\t\tif (e.childNodes == undefined) return;\n"
-    "\t\tfor (var i = 0, c = e.childNodes; i < c.length; i++) {\n"
-    "\t\t\tzoom_child(c[i], x - 10, ratio);\n"
-    "\t\t}\n"
-    "\t}\n"
-    "\tfunction zoom_parent(e) {\n"
-    "\t\tif (e.attributes) {\n"
-    "\t\t\tif (e.attributes.x != undefined) {\n"
-    "\t\t\t\torig_save(e, \"x\");\n"
-    "\t\t\t\te.attributes.x.value = 10;\n"
-    "\t\t\t}\n"
-    "\t\t\tif (e.attributes.width != undefined) {\n"
-    "\t\t\t\torig_save(e, \"width\");\n"
-    "\t\t\t\te.attributes.width.value = parseInt(svg.width.baseVal.value) - (10 * 2);\n"
-    "\t\t\t}\n"
-    "\t\t}\n"
-    "\t\tif (e.childNodes == undefined) return;\n"
-    "\t\tfor (var i = 0, c = e.childNodes; i < c.length; i++) {\n"
-    "\t\t\tzoom_parent(c[i]);\n"
-    "\t\t}\n"
-    "\t}\n"
-    "\tfunction zoom(node) {\n"
-    "\t\tvar attr = find_child(node, \"rect\").attributes;\n"
-    "\t\tvar width = parseFloat(attr.width.value);\n"
-    "\t\tvar xmin = parseFloat(attr.x.value);\n"
-    "\t\tvar xmax = parseFloat(xmin + width);\n"
-    "\t\tvar ymin = parseFloat(attr.y.value);\n"
-    "\t\tvar ratio = (svg.width.baseVal.value - 2 * 10) / width;\n"
-    "\n"
-    "\t\t// XXX: Workaround for JavaScript float issues (fix me)\n"
-    "\t\tvar fudge = 0.0001;\n"
-    "\n"
-    "\t\tunzoombtn.classList.remove(\"hide\");\n"
-    "\n"
-    "\t\tvar el = document.getElementById(\"frames\").children;\n"
-    "\t\tfor (var i = 0; i < el.length; i++) {\n"
-    "\t\t\tvar e = el[i];\n"
-    "\t\t\tvar a = find_child(e, \"rect\").attributes;\n"
-    "\t\t\tvar ex = parseFloat(a.x.value);\n"
-    "\t\t\tvar ew = parseFloat(a.width.value);\n"
-    "\t\t\tvar upstack;\n"
-    "\t\t\t// Is it an ancestor\n"
-    "\t\t\tif (%d == 0) {\n"
-    "\t\t\t\tupstack = parseFloat(a.y.value) > ymin;\n"
-    "\t\t\t} else {\n"
-    "\t\t\t\tupstack = parseFloat(a.y.value) < ymin;\n"
-    "\t\t\t}\n"
-    "\t\t\tif (upstack) {\n"
-    "\t\t\t\t// Direct ancestor\n"
-    "\t\t\t\tif (ex <= xmin && (ex+ew+fudge) >= xmax) {\n"
-    "\t\t\t\t\te.classList.add(\"parent\");\n"
-    "\t\t\t\t\tzoom_parent(e);\n"
-    "\t\t\t\t\tupdate_text(e);\n"
-    "\t\t\t\t}\n"
-    "\t\t\t\t// not in current path\n"
-    "\t\t\t\telse\n"
-    "\t\t\t\t\te.classList.add(\"hide\");\n"
-    "\t\t\t}\n"
-    "\t\t\t// Children maybe\n"
-    "\t\t\telse {\n"
-    "\t\t\t\t// no common path\n"
-    "\t\t\t\tif (ex < xmin || ex + fudge >= xmax) {\n"
-    "\t\t\t\t\te.classList.add(\"hide\");\n"
-    "\t\t\t\t}\n"
-    "\t\t\t\telse {\n"
-    "\t\t\t\t\tzoom_child(e, xmin, ratio);\n"
-    "\t\t\t\t\tupdate_text(e);\n"
-    "\t\t\t\t}\n"
-    "\t\t\t}\n"
-    "\t\t}\n"
-    "\t}\n"
-    "\tfunction unzoom() {\n"
-    "\t\tunzoombtn.classList.add(\"hide\");\n"
-    "\t\tvar el = document.getElementById(\"frames\").children;\n"
-    "\t\tfor(var i = 0; i < el.length; i++) {\n"
-    "\t\t\tel[i].classList.remove(\"parent\");\n"
-    "\t\t\tel[i].classList.remove(\"hide\");\n"
-    "\t\t\tzoom_reset(el[i]);\n"
-    "\t\t\tupdate_text(el[i]);\n"
-    "\t\t}\n"
+    "\tcanvas.onmouseout = function() {\n"
+    "\t\thl.style.display = 'none';\n"
+    "\t\tstatus.textContent = '\\xa0';\n"
+    "\t\tcanvas.title = '';\n"
+    "\t\tcanvas.style.cursor = '';\n"
+    "\t\tcanvas.onclick = '';\n"
     "\t}\n"
     "\n"
-    "\t// search\n"
-    "\tfunction reset_search() {\n"
-    "\t\tvar el = document.querySelectorAll(\"#frames rect\");\n"
-    "\t\tfor (var i = 0; i < el.length; i++) {\n"
-    "\t\t\torig_load(el[i], \"fill\")\n"
-    "\t\t}\n"
+    "\tdocument.getElementById('reverse').onclick = function() {\n"
+    "\t\treverse = !reverse;\n"
+    "\t\trender();\n"
     "\t}\n"
-    "\tfunction search_prompt() {\n"
-    "\t\tif (!searching) {\n"
-    "\t\t\tvar term = prompt(\"Enter a search term (regexp \" +\n"
-    "\t\t\t    \"allowed, eg: ^ext4_)\", \"\");\n"
-    "\t\t\tif (term != null) {\n"
-    "\t\t\t\tsearch(term)\n"
-    "\t\t\t}\n"
-    "\t\t} else {\n"
-    "\t\t\treset_search();\n"
-    "\t\t\tsearching = 0;\n"
-    "\t\t\tsearchbtn.classList.remove(\"show\");\n"
-    "\t\t\tsearchbtn.firstChild.nodeValue = \"Search\"\n"
-    "\t\t\tmatchedtxt.classList.add(\"hide\");\n"
-    "\t\t\tmatchedtxt.firstChild.nodeValue = \"\"\n"
-    "\t\t}\n"
+    "\n"
+    "\tdocument.getElementById('search').onclick = function() {\n"
+    "\t\tsearch(true);\n"
     "\t}\n"
-    "\tfunction search(term) {\n"
-    "\t\tvar re = new RegExp(term);\n"
-    "\t\tvar el = document.getElementById(\"frames\").children;\n"
-    "\t\tvar matches = new Object();\n"
-    "\t\tvar maxwidth = 0;\n"
-    "\t\tfor (var i = 0; i < el.length; i++) {\n"
-    "\t\t\tvar e = el[i];\n"
-    "\t\t\tvar func = g_to_func(e);\n"
-    "\t\t\tvar rect = find_child(e, \"rect\");\n"
-    "\t\t\tif (func == null || rect == null)\n"
-    "\t\t\t\tcontinue;\n"
     "\n"
-    "\t\t\t// Save max width. Only works as we have a root frame\n"
-    "\t\t\tvar w = parseFloat(rect.attributes.width.value);\n"
-    "\t\t\tif (w > maxwidth)\n"
-    "\t\t\t\tmaxwidth = w;\n"
-    "\n"
-    "\t\t\tif (func.match(re)) {\n"
-    "\t\t\t\t// highlight\n"
-    "\t\t\t\tvar x = parseFloat(rect.attributes.x.value);\n"
-    "\t\t\t\torig_save(rect, \"fill\");\n"
-    "\t\t\t\trect.attributes.fill.value = \"rgb(230,0,230)\";\n"
-    "\n"
-    "\t\t\t\t// remember matches\n"
-    "\t\t\t\tif (matches[x] == undefined) {\n"
-    "\t\t\t\t\tmatches[x] = w;\n"
-    "\t\t\t\t} else {\n"
-    "\t\t\t\t\tif (w > matches[x]) {\n"
-    "\t\t\t\t\t\t// overwrite with parent\n"
-    "\t\t\t\t\t\tmatches[x] = w;\n"
-    "\t\t\t\t\t}\n"
-    "\t\t\t\t}\n"
-    "\t\t\t\tsearching = 1;\n"
-    "\t\t\t}\n"
-    "\t\t}\n"
-    "\t\tif (!searching)\n"
-    "\t\t\treturn;\n"
-    "\n"
-    "\t\tsearchbtn.classList.add(\"show\");\n"
-    "\t\tsearchbtn.firstChild.nodeValue = \"Reset Search\";\n"
-    "\n"
-    "\t\t// calculate percent matched, excluding vertical overlap\n"
-    "\t\tvar count = 0;\n"
-    "\t\tvar lastx = -1;\n"
-    "\t\tvar lastw = 0;\n"
-    "\t\tvar keys = Array();\n"
-    "\t\tfor (k in matches) {\n"
-    "\t\t\tif (matches.hasOwnProperty(k))\n"
-    "\t\t\t\tkeys.push(k);\n"
-    "\t\t}\n"
-    "\t\t// sort the matched frames by their x location\n"
-    "\t\t// ascending, then width descending\n"
-    "\t\tkeys.sort(function(a, b){\n"
-    "\t\t\treturn a - b;\n"
-    "\t\t});\n"
-    "\t\t// Step through frames saving only the biggest bottom-up frames\n"
-    "\t\t// thanks to the sort order. This relies on the tree property\n"
-    "\t\t// where children are always smaller than their parents.\n"
-    "\t\tvar fudge = 0.0001;\t// JavaScript floating point\n"
-    "\t\tfor (var k in keys) {\n"
-    "\t\t\tvar x = parseFloat(keys[k]);\n"
-    "\t\t\tvar w = matches[keys[k]];\n"
-    "\t\t\tif (x >= lastx + lastw - fudge) {\n"
-    "\t\t\t\tcount += w;\n"
-    "\t\t\t\tlastx = x;\n"
-    "\t\t\t\tlastw = w;\n"
-    "\t\t\t}\n"
-    "\t\t}\n"
-    "\t\t// display matched percent\n"
-    "\t\tmatchedtxt.classList.remove(\"hide\");\n"
-    "\t\tvar pct = 100 * count / maxwidth;\n"
-    "\t\tif (pct != 100) pct = pct.toFixed(1)\n"
-    "\t\tmatchedtxt.firstChild.nodeValue = \"Matched: \" + pct + \"%%\";\n"
+    "\tdocument.getElementById('reset').onclick = function() {\n"
+    "\t\tsearch(false);\n"
     "\t}\n"
-    "]]>\n"
-    "</script>\n"
-    "<rect x=\"0\" y=\"0\" width=\"100%%\" height=\"100%%\" fill=\"rgb(240,240,220)\"/>\n"
-    "<text id=\"title\" x=\"%d\" y=\"%d\">%s</text>\n"
-    "<text id=\"details\" x=\"%d\" y=\"%d\"> </text>\n"
-    "<text id=\"unzoom\" x=\"%d\" y=\"%d\" class=\"hide\">Reset Zoom</text>\n"
-    "<text id=\"search\" x=\"%d\" y=\"%d\">Search</text>\n"
-    "<text id=\"matched\" x=\"%d\" y=\"%d\"> </text>\n"
-    "<g id=\"frames\">\n";
+    "\n"
+    "\twindow.onkeydown = function() {\n"
+    "\t\tif (event.ctrlKey && event.keyCode === 70) {\n"
+    "\t\t\tevent.preventDefault();\n"
+    "\t\t\tsearch(true);\n"
+    "\t\t} else if (event.keyCode === 27) {\n"
+    "\t\t\tsearch(false);\n"
+    "\t\t}\n"
+    "\t}\n";
+
+static const char FLAMEGRAPH_FOOTER[] =
+    "render();\n"
+    "</script></body></html>\n";
+
 
 static const char TREE_HEADER[] =
     "<!DOCTYPE html>\n"
@@ -418,19 +294,19 @@ static const char TREE_HEADER[] =
     "    font-weight: bold;\n"
     "    background-color: #D9D9D9;\n"
     "}\n"
-    ".green {\n"
+    ".t0 {\n"
     "    color: #32c832;\n"
     "}\n"
-    ".aqua {\n"
+    ".t1 {\n"
     "    color: #32a5a5;\n"
     "}\n"
-    ".brown {\n"
+    ".t2 {\n"
     "    color: #be5a00;\n"
     "}\n"
-    ".yellow {\n"
+    ".t3 {\n"
     "    color: #afaf32;\n"
     "}\n"
-    ".red {\n"
+    ".t4 {\n"
     "    color: #c83232;\n"
     "}\n"
     "ul.tree li > div {\n"
@@ -537,27 +413,11 @@ class StringUtils {
         return len >= suffixlen && s.compare(len - suffixlen, suffixlen, suffix) == 0; 
     }
 
-    static std::string trim(const std::string& s, size_t maxchars) {
-        if (maxchars < 3) {
-            return "";
-        } else if (s.length() > maxchars) {
-            return s.substr(0, maxchars - 2) + "..";
-        } else {
-            return s;
-        }
-    }
-
     static void replace(std::string& s, char c, const char* replacement) {
         for (size_t i = 0; (i = s.find(c, i)) != std::string::npos; i++) {
             s.replace(i, 1, replacement);
         }
     }
-
-    static void escape(std::string& s) {
-        replace(s, '&', "&amp;");
-        replace(s, '<', "&lt;");
-        replace(s, '>', "&gt;");
-    }
 };
 
 
@@ -588,183 +448,129 @@ class Format {
 };
 
 
-class Palette {
-  private:
-    const char* _name;
-    int _base;
-    int _r, _g, _b;
-
+class Node {
   public:
-    Palette(const char* name, int base, int r, int g, int b) : _name(name), _base(base), _r(r), _g(g), _b(b) {
+    std::string _name;
+    const Trie* _trie;
+
+    Node(const std::string& name, const Trie& trie) : _name(name), _trie(&trie) {
     }
 
-    const char* name() const {
-        return _name;
-    }
-
-    int pickColor() const {
-        double value = double(rand()) / RAND_MAX;
-        return _base + (int(_r * value) << 16 | int(_g * value) << 8 | int(_b * value));
+    bool operator<(const Node& other) const {
+        return _trie->_total > other._trie->_total;
     }
 };
 
 
 void FlameGraph::dump(std::ostream& out, bool tree) {
-    _scale = (_imagewidth - 20) / (double)_root._total;
-    _pct = 100 / (double)_root._total;
-
-    u64 cutoff = (u64)ceil(_minwidth / _scale);
-    _imageheight = _frameheight * _root.depth(cutoff) + 70;
+    _mintotal = _minwidth == 0 && tree ? _root._total / 1000 : (u64)(_root._total * _minwidth / 100);
+    int depth = _root.depth(_mintotal);
 
     if (tree) {
-        printTreeHeader(out);
+        char buf[sizeof(TREE_HEADER) + 256];
+        snprintf(buf, sizeof(buf) - 1, TREE_HEADER,
+                 _reverse ? "Backtrace" : "Call tree",
+                 _counter ==  COUNTER_SAMPLES ? "samples" : "counter",
+                 Format().thousands(_root._total));
+        out << buf;
+
         printTreeFrame(out, _root, 0);
-        printTreeFooter(out);
+
+        out << TREE_FOOTER;
     } else {
-        printHeader(out);
-        printFrame(out, "all", _root, 10, _reverse ? 35 : (_imageheight - _frameheight - 35));
-        printFooter(out);
+        char buf[sizeof(FLAMEGRAPH_HEADER) + 256];
+        snprintf(buf, sizeof(buf) - 1, FLAMEGRAPH_HEADER, _title, depth * 16, _reverse ? "true" : "false", depth);
+        out << buf;
+
+        printFrame(out, "all", _root, 0, 0);
+
+        out << FLAMEGRAPH_FOOTER;
     }
 }
 
-void FlameGraph::printHeader(std::ostream& out) {
-    char buf[sizeof(SVG_HEADER) + 256];
-    int x0 = _imagewidth / 2;
-    int x1 = 10;
-    int x2 = _imagewidth - 110;
-    int y0 = 24;
-    int y1 = _imageheight - 17;
+void FlameGraph::printFrame(std::ostream& out, const std::string& name, const Trie& f, int level, u64 x) {
+    std::string name_copy = name;
+    int type = frameType(name_copy);
+    StringUtils::replace(name_copy, '\'', "\\'");
 
-    sprintf(buf, SVG_HEADER,
-            _imagewidth, _imageheight, _imagewidth, _imageheight, _reverse,
-            x0, y0, _title, x1, y1, x1, y0, x2, y0, x2, y1);
-    out << buf;
-}
+    snprintf(_buf, sizeof(_buf) - 1, "f(%d,%llu,%llu,%d,'%s')\n", level, x, f._total, type, name_copy.c_str());
+    out << _buf;
 
-void FlameGraph::printFooter(std::ostream& out) {
-    out << "</g>\n</svg>\n";
-}
-
-double FlameGraph::printFrame(std::ostream& out, const std::string& name, const Trie& f, double x, double y) {
-    double framewidth = f._total * _scale;
-
-    // Skip too narrow frames, they are not important
-    if (framewidth >= _minwidth) {
-        std::string full_title = name;
-        int color = selectFramePalette(full_title).pickColor();
-        std::string short_title = StringUtils::trim(full_title, size_t(framewidth / 7));
-        StringUtils::escape(full_title);
-        StringUtils::escape(short_title);
-
-        // Compensate rounding error in frame width
-        double w = (round((x + framewidth) * 10) - round(x * 10)) / 10.0;
-
-        snprintf(_buf, sizeof(_buf),
-            "<g>\n"
-            "<title>%s (%s samples, %.2f%%)</title><rect x=\"%.1f\" y=\"%.1f\" width=\"%.1f\" height=\"%d\" fill=\"#%06x\" rx=\"2\" ry=\"2\"/>\n"
-            "<text x=\"%.1f\" y=\"%.1f\">%s</text>\n"
-            "</g>\n",
-            full_title.c_str(), Format().thousands(f._total), f._total * _pct, x, y, w, _frameheight - 1, color,
-            x + 3, y + 3 + _frameheight * 0.5, short_title.c_str());
-        out << _buf;
-
-        x += f._self * _scale;
-        y += _reverse ? _frameheight : -_frameheight;
-
-        for (std::map<std::string, Trie>::const_iterator it = f._children.begin(); it != f._children.end(); ++it) {
-            x += printFrame(out, it->first, it->second, x, y);
+    x += f._self;
+    for (std::map<std::string, Trie>::const_iterator it = f._children.begin(); it != f._children.end(); ++it) {
+        if (it->second._total >= _mintotal) {
+            printFrame(out, it->first, it->second, level + 1, x);
         }
+        x += it->second._total;
     }
-
-    return framewidth;
 }
 
-void FlameGraph::printTreeHeader(std::ostream& out) {
-    char buf[sizeof(TREE_HEADER) + 256];
-    const char* title = _reverse ? "Backtrace" : "Call tree";
-    const char* counter = _counter ==  COUNTER_SAMPLES ? "samples" : "counter";
-    sprintf(buf, TREE_HEADER, title, counter, Format().thousands(_root._total));
-    out << buf;
-}
-
-void FlameGraph::printTreeFooter(std::ostream& out) {   
-    out << TREE_FOOTER;
-}
-
-bool FlameGraph::printTreeFrame(std::ostream& out, const Trie& f, int depth) {
-    double framewidth = f._total * _scale;
-    if (framewidth < _minwidth) {
-        return false;
-    }
-
+void FlameGraph::printTreeFrame(std::ostream& out, const Trie& f, int level) {
     std::vector<Node> subnodes;
     for (std::map<std::string, Trie>::const_iterator it = f._children.begin(); it != f._children.end(); ++it) {
         subnodes.push_back(Node(it->first, it->second));
     }
     std::sort(subnodes.begin(), subnodes.end());
 
+    double pct = 100.0 / _root._total;
     for (size_t i = 0; i < subnodes.size(); i++) {
-        std::string full_title = subnodes[i]._name;
+        std::string name = subnodes[i]._name;
         const Trie* trie = subnodes[i]._trie;
-        const char* color = selectFramePalette(full_title).name();
-        StringUtils::escape(full_title);
+
+        int type = frameType(name);
+        StringUtils::replace(name, '&', "&amp;");
+        StringUtils::replace(name, '<', "&lt;");
+        StringUtils::replace(name, '>', "&gt;");
 
         if (_reverse) {
-            snprintf(_buf, sizeof(_buf),
-                     "<li><div>[%d] %.2f%% %s</div><span class=\"%s\"> %s</span>\n",
-                     depth,
-                     trie->_total * _pct, Format().thousands(trie->_total),
-                     color, full_title.c_str());
+            snprintf(_buf, sizeof(_buf) - 1,
+                     "<li><div>[%d] %.2f%% %s</div><span class=\"t%d\"> %s</span>\n",
+                     level,
+                     trie->_total * pct, Format().thousands(trie->_total),
+                     type, name.c_str());
         } else {
-            snprintf(_buf, sizeof(_buf),
-                     "<li><div>[%d] %.2f%% %s self: %.2f%% %s</div><span class=\"%s\"> %s</span>\n",
-                     depth,
-                     trie->_total * _pct, Format().thousands(trie->_total),
-                     trie->_self * _pct, Format().thousands(trie->_self),
-                     color, full_title.c_str());
+            snprintf(_buf, sizeof(_buf) - 1,
+                     "<li><div>[%d] %.2f%% %s self: %.2f%% %s</div><span class=\"t%d\"> %s</span>\n",
+                     level,
+                     trie->_total * pct, Format().thousands(trie->_total),
+                     trie->_self * pct, Format().thousands(trie->_self),
+                     type, name.c_str());
         }
         out << _buf;
 
         if (trie->_children.size() > 0) {
             out << "<ul>\n";
-            if (!printTreeFrame(out, *trie, depth + 1)) {
+            if (trie->_total >= _mintotal) {
+                printTreeFrame(out, *trie, level + 1);
+            } else {
                 out << "<li>...\n";
             }
             out << "</ul>\n";
         }
     }
-
-    return true;
 }
 
-const Palette& FlameGraph::selectFramePalette(std::string& name) {
-    static const Palette
-        green ("green",  0x50e150, 30, 30, 30),
-        aqua  ("aqua",   0x50bebe, 30, 30, 30),
-        brown ("brown",  0xe17d00, 30, 30,  0),
-        yellow("yellow", 0xc8c83c, 30, 30, 10),
-        red   ("red",    0xe15a5a, 30, 40, 40);
-
+int FlameGraph::frameType(std::string& name) {
     if (StringUtils::endsWith(name, "_[j]", 4)) {
         // Java compiled frame
         name = name.substr(0, name.length() - 4);
-        return green;
+        return 0;
     } else if (StringUtils::endsWith(name, "_[i]", 4)) {
         // Java inlined frame
         name = name.substr(0, name.length() - 4);
-        return aqua;
+        return 1;
     } else if (StringUtils::endsWith(name, "_[k]", 4)) {
         // Kernel function
         name = name.substr(0, name.length() - 4);
-        return brown;
+        return 2;
     } else if (name.find("::") != std::string::npos || name.compare(0, 2, "-[") == 0 || name.compare(0, 2, "+[") == 0) {
         // C++ function or Objective C method
-        return yellow;
+        return 3;
     } else if ((int)name.find('/') > 0 || ((int)name.find('.') > 0 && name[0] >= 'A' && name[0] <= 'Z')) {
         // Java regular method
-        return green;
+        return 0;
     } else {
         // Other native code
-        return red;
+        return 4;
     }
 }

src/flameGraph.h

@@ -57,55 +57,30 @@ class Trie {
     }
 };
 
-class Node {
-  public:
-    std::string _name;
-    const Trie* _trie;
-
-    Node(std::string name, const Trie& trie) : _name(name), _trie(&trie) {
-    }
-
-    bool operator<(const Node& other) const {
-        return _trie->_total > other._trie->_total;
-    }
-};
-
-
-class Palette;
-
 
 class FlameGraph {
   private:
     Trie _root;
     char _buf[4096];
+    u64 _mintotal;
 
     const char* _title;
     Counter _counter;
-    int _imagewidth;
-    int _imageheight;
-    int _frameheight;
     double _minwidth;
-    double _scale;
-    double _pct;
     bool _reverse;
 
-    void printHeader(std::ostream& out);
-    void printFooter(std::ostream& out);
-    double printFrame(std::ostream& out, const std::string& name, const Trie& f, double x, double y);
-    void printTreeHeader(std::ostream& out);
-    void printTreeFooter(std::ostream& out);
-    bool printTreeFrame(std::ostream& out, const Trie& f, int depth);
-    const Palette& selectFramePalette(std::string& name);
+    void printFrame(std::ostream& out, const std::string& name, const Trie& f, int level, u64 x);
+    void printTreeFrame(std::ostream& out, const Trie& f, int level);
+    int frameType(std::string& name);
 
   public:
-    FlameGraph(const char* title, Counter counter, int width, int height, double minwidth, bool reverse) :
+    FlameGraph(const char* title, Counter counter, double minwidth, bool reverse) :
         _root(),
         _title(title),
         _counter(counter),
-        _imagewidth(width),
-        _frameheight(height),
         _minwidth(minwidth),
         _reverse(reverse) {
+        _buf[sizeof(_buf) - 1] = 0;
     }
 
     Trie* root() {

src/flightRecorder.h

@@ -17,8 +17,9 @@
 #ifndef _FLIGHTRECORDER_H
 #define _FLIGHTRECORDER_H
 
+#include "arch.h"
 #include "arguments.h"
-
+#include "event.h"
 
 class Recording;
 
@@ -30,10 +31,15 @@ class FlightRecorder {
     FlightRecorder() : _rec(NULL) {
     }
 
-    Error start(const char* file);
+    Error start(Arguments& args, bool reset);
     void stop();
 
-    void recordExecutionSample(int lock_index, int tid, int call_trace_id);
+    bool active() {
+        return _rec != NULL;
+    }
+
+    void recordEvent(int lock_index, int tid, u32 call_trace_id,
+                     int event_type, Event* event, u64 counter);
 };
 
 #endif // _FLIGHTRECORDER_H

src/frameName.cpp

@@ -19,12 +19,67 @@
 #include <stdlib.h>
 #include <string.h>
 #include "frameName.h"
-#include "arguments.h"
+#include "profiler.h"
 #include "vmStructs.h"
 
 
-FrameName::FrameName(int style, Mutex& thread_names_lock, ThreadMap& thread_names) :
+Matcher::Matcher(const char* pattern) {
+    if (pattern[0] == '*') {
+        _type = MATCH_ENDS_WITH;
+        _pattern = strdup(pattern + 1);
+    } else {
+        _type = MATCH_EQUALS;
+        _pattern = strdup(pattern);
+    }
+
+    _len = strlen(_pattern);
+    if (_len > 0 && _pattern[_len - 1] == '*') {
+        _type = _type == MATCH_EQUALS ? MATCH_STARTS_WITH : MATCH_CONTAINS;
+        _pattern[--_len] = 0;
+    }
+}
+
+Matcher::~Matcher() {
+    free(_pattern);
+}
+
+Matcher::Matcher(const Matcher& m) {
+    _type = m._type;
+    _pattern = strdup(m._pattern);
+    _len = m._len;
+}
+
+Matcher& Matcher::operator=(const Matcher& m) {
+    free(_pattern);
+
+    _type = m._type;
+    _pattern = strdup(m._pattern);
+    _len = m._len;
+
+    return *this;
+}
+
+bool Matcher::matches(const char* s) {
+    switch (_type) {
+        case MATCH_EQUALS:
+            return strcmp(s, _pattern) == 0;
+        case MATCH_CONTAINS:
+            return strstr(s, _pattern) != NULL;
+        case MATCH_STARTS_WITH:
+            return strncmp(s, _pattern, _len) == 0;
+        case MATCH_ENDS_WITH:
+            int slen = strlen(s);
+            return slen >= _len && strcmp(s + slen - _len, _pattern) == 0;
+    }
+    return false;
+}
+
+
+FrameName::FrameName(Arguments& args, int style, Mutex& thread_names_lock, ThreadMap& thread_names) :
     _cache(),
+    _class_names(),
+    _include(),
+    _exclude(),
     _style(style),
     _thread_names_lock(thread_names_lock),
     _thread_names(thread_names)
@@ -32,12 +87,31 @@ FrameName::FrameName(int style, Mutex& thread_names_lock, ThreadMap& thread_name
     // Require printf to use standard C format regardless of system locale
     _saved_locale = uselocale(newlocale(LC_NUMERIC_MASK, "C", (locale_t)0));
     memset(_buf, 0, sizeof(_buf));
+
+    buildFilter(_include, args._buf, args._include);
+    buildFilter(_exclude, args._buf, args._exclude);
+
+    Profiler::_instance.classMap()->collect(_class_names);
 }
 
 FrameName::~FrameName() {
     freelocale(uselocale(_saved_locale));
 }
 
+void FrameName::buildFilter(std::vector<Matcher>& vector, const char* base, int offset) {
+    while (offset != 0) {
+        vector.push_back(base + offset);
+        offset = ((int*)(base + offset))[-1];
+    }
+}
+
+char* FrameName::truncate(char* name, int max_length) {
+    if (strlen(name) > max_length && max_length >= 4) {
+        strcpy(name + max_length - 4, "...)");
+    }
+    return name;
+}
+
 const char* FrameName::cppDemangle(const char* name) {
     if (name != NULL && name[0] == '_' && name[1] == 'Z') {
         int status;
@@ -68,10 +142,10 @@ char* FrameName::javaMethodName(jmethodID method) {
         result = javaClassName(class_name + 1, strlen(class_name) - 2, _style);
         strcat(result, ".");
         strcat(result, method_name);
-        if (_style & STYLE_SIGNATURES) strcat(result, method_sig);
+        if (_style & STYLE_SIGNATURES) strcat(result, truncate(method_sig, 255));
         if (_style & STYLE_ANNOTATE) strcat(result, "_[j]");
     } else {
-        snprintf(_buf, sizeof(_buf), "[jvmtiError %d]", err);
+        snprintf(_buf, sizeof(_buf) - 1, "[jvmtiError %d]", err);
         result = _buf;
     }
 
@@ -130,7 +204,7 @@ char* FrameName::javaClassName(const char* symbol, int length, int style) {
     return result;
 }
 
-const char* FrameName::name(ASGCT_CallFrame& frame) {
+const char* FrameName::name(ASGCT_CallFrame& frame, bool for_matching) {
     if (frame.method_id == NULL) {
         return "[unknown]";
     }
@@ -139,32 +213,34 @@ const char* FrameName::name(ASGCT_CallFrame& frame) {
         case BCI_NATIVE_FRAME:
             return cppDemangle((const char*)frame.method_id);
 
-        case BCI_SYMBOL: {
-            VMSymbol* symbol = (VMSymbol*)frame.method_id;
-            char* class_name = javaClassName(symbol->body(), symbol->length(), _style | STYLE_DOTTED);
-            return strcat(class_name, _style & STYLE_DOTTED ? "" : "_[i]");
-        }
-
-        case BCI_SYMBOL_OUTSIDE_TLAB: {
-            VMSymbol* symbol = (VMSymbol*)((uintptr_t)frame.method_id ^ 1);
-            char* class_name = javaClassName(symbol->body(), symbol->length(), _style | STYLE_DOTTED);
-            return strcat(class_name, _style & STYLE_DOTTED ? " (out)" : "_[k]");
+        case BCI_ALLOC:
+        case BCI_ALLOC_OUTSIDE_TLAB:
+        case BCI_LOCK:
+        case BCI_PARK: {
+            const char* symbol = _class_names[(uintptr_t)frame.method_id];
+            char* class_name = javaClassName(symbol, strlen(symbol), _style | STYLE_DOTTED);
+            if (!for_matching && !(_style & STYLE_DOTTED)) {
+                strcat(class_name, frame.bci == BCI_ALLOC_OUTSIDE_TLAB ? "_[k]" : "_[i]");
+            }
+            return class_name;
         }
 
         case BCI_THREAD_ID: {
             int tid = (int)(uintptr_t)frame.method_id;
             MutexLocker ml(_thread_names_lock);
             ThreadMap::iterator it = _thread_names.find(tid);
-            if (it != _thread_names.end()) {
-                snprintf(_buf, sizeof(_buf), "[%s tid=%d]", it->second.c_str(), tid);
+            if (for_matching) {
+                return it != _thread_names.end() ? it->second.c_str() : "";
+            } else if (it != _thread_names.end()) {
+                snprintf(_buf, sizeof(_buf) - 1, "[%s tid=%d]", it->second.c_str(), tid);
             } else {
-                snprintf(_buf, sizeof(_buf), "[tid=%d]", tid);
+                snprintf(_buf, sizeof(_buf) - 1, "[tid=%d]", tid);
             }
             return _buf;
         }
 
         case BCI_ERROR: {
-            snprintf(_buf, sizeof(_buf), "[%s]", (const char*)frame.method_id);
+            snprintf(_buf, sizeof(_buf) - 1, "[%s]", (const char*)frame.method_id);
             return _buf;
         }
 
@@ -180,3 +256,22 @@ const char* FrameName::name(ASGCT_CallFrame& frame) {
         }
     }
 }
+
+bool FrameName::include(const char* frame_name) {
+    for (int i = 0; i < _include.size(); i++) {
+        if (_include[i].matches(frame_name)) {
+            return true;
+        }
+    }
+    return false;
+}
+
+bool FrameName::exclude(const char* frame_name) {
+    for (int i = 0; i < _exclude.size(); i++) {
+        if (_exclude[i].matches(frame_name)) {
+            return true;
+        }
+    }
+    return false;
+}
+

src/frameName.h

@@ -20,7 +20,9 @@
 #include <jvmti.h>
 #include <locale.h>
 #include <map>
+#include <vector>
 #include <string>
+#include "arguments.h"
 #include "mutex.h"
 #include "vmEntry.h"
 
@@ -31,25 +33,63 @@
 
 typedef std::map<jmethodID, std::string> JMethodCache;
 typedef std::map<int, std::string> ThreadMap;
+typedef std::map<unsigned int, const char*> ClassMap;
+
+
+enum MatchType {
+  MATCH_EQUALS,
+  MATCH_CONTAINS,
+  MATCH_STARTS_WITH,
+  MATCH_ENDS_WITH
+};
+
+
+class Matcher {
+  private:
+    MatchType _type;
+    char* _pattern;
+    int _len;
+
+  public:
+    Matcher(const char* pattern);
+    ~Matcher();
+
+    Matcher(const Matcher& m);
+    Matcher& operator=(const Matcher& m);
+
+    bool matches(const char* s);
+};
+
 
 class FrameName {
   private:
     JMethodCache _cache;
+    ClassMap _class_names;
+    std::vector<Matcher> _include;
+    std::vector<Matcher> _exclude;
     char _buf[800];  // must be large enough for class name + method name + method signature
     int _style;
     Mutex& _thread_names_lock;
     ThreadMap& _thread_names;
     locale_t _saved_locale;
 
+    void buildFilter(std::vector<Matcher>& vector, const char* base, int offset);
+    char* truncate(char* name, int max_length);
     const char* cppDemangle(const char* name);
     char* javaMethodName(jmethodID method);
     char* javaClassName(const char* symbol, int length, int style);
 
   public:
-    FrameName(int style, Mutex& thread_names_lock, ThreadMap& thread_names);
+    FrameName(Arguments& args, int style, Mutex& thread_names_lock, ThreadMap& thread_names);
     ~FrameName();
 
-    const char* name(ASGCT_CallFrame& frame);
+    const char* name(ASGCT_CallFrame& frame, bool for_matching = false);
+
+    bool hasIncludeList() { return !_include.empty(); }
+    bool hasExcludeList() { return !_exclude.empty(); }
+
+    bool include(const char* frame_name);
+    bool exclude(const char* frame_name);
 };
 
 #endif // _FRAMENAME_H

src/instrument.cpp

@@ -0,0 +1,593 @@
+/*
+ * Copyright 2019 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <arpa/inet.h>
+#include <stdlib.h>
+#include <string.h>
+#include "arch.h"
+#include "os.h"
+#include "profiler.h"
+#include "vmEntry.h"
+#include "instrument.h"
+
+
+// A class with a single native recordSample() method
+static const char INSTRUMENT_CLASS[] =
+    "\xCA\xFE\xBA\xBE"                     // magic
+    "\x00\x00\x00\x32"                     // version: 50
+    "\x00\x07"                             // constant_pool_count: 7
+    "\x07\x00\x02"                         //   #1 = CONSTANT_Class: #2
+    "\x01\x00\x17one/profiler/Instrument"  //   #2 = CONSTANT_Utf8: "one/profiler/Instrument"
+    "\x07\x00\x04"                         //   #3 = CONSTANT_Class: #4
+    "\x01\x00\x10java/lang/Object"         //   #4 = CONSTANT_Utf8: "java/lang/Object"
+    "\x01\x00\x0CrecordSample"             //   #5 = CONSTANT_Utf8: "recordSample"
+    "\x01\x00\x03()V"                      //   #6 = CONSTANT_Utf8: "()V"
+    "\x00\x21"                             // access_flags: public super
+    "\x00\x01"                             // this_class: #1
+    "\x00\x03"                             // super_class: #3
+    "\x00\x00"                             // interfaces_count: 0
+    "\x00\x00"                             // fields_count: 0
+    "\x00\x01"                             // methods_count: 1
+    "\x01\x09"                             //   access_flags: public static native
+    "\x00\x05"                             //   name_index: #5
+    "\x00\x06"                             //   descriptor_index: #6
+    "\x00\x00"                             //   attributes_count: 0
+    "\x00";                                // attributes_count: 0
+
+
+enum ConstantTag {
+    CONSTANT_Utf8 = 1,
+    CONSTANT_Integer = 3,
+    CONSTANT_Float = 4,
+    CONSTANT_Long = 5,
+    CONSTANT_Double = 6,
+    CONSTANT_Class = 7,
+    CONSTANT_String = 8,
+    CONSTANT_Fieldref = 9,
+    CONSTANT_Methodref = 10,
+    CONSTANT_InterfaceMethodref = 11,
+    CONSTANT_NameAndType = 12,
+    CONSTANT_MethodHandle = 15,
+    CONSTANT_MethodType = 16,
+    CONSTANT_Dynamic = 17,
+    CONSTANT_InvokeDynamic = 18,
+    CONSTANT_Module = 19,
+    CONSTANT_Package = 20
+};
+
+class Constant {
+  private:
+    u8 _tag;
+    u8 _info[2];
+
+  public:
+    u8 tag() {
+        return _tag;
+    }
+
+    int slots() {
+        return _tag == CONSTANT_Long || _tag == CONSTANT_Double ? 2 : 1;
+    }
+
+    u16 info() {
+        return (u16)_info[0] << 8 | (u16)_info[1];
+    }
+
+    int length() {
+        switch (_tag) {
+            case CONSTANT_Utf8:
+                return 2 + info();
+            case CONSTANT_Integer:
+            case CONSTANT_Float:
+            case CONSTANT_Fieldref:
+            case CONSTANT_Methodref:
+            case CONSTANT_InterfaceMethodref:
+            case CONSTANT_NameAndType:
+            case CONSTANT_Dynamic:
+            case CONSTANT_InvokeDynamic:
+                return 4;
+            case CONSTANT_Long:
+            case CONSTANT_Double:
+                return 8;
+            case CONSTANT_Class:
+            case CONSTANT_String:
+            case CONSTANT_MethodType:
+            case CONSTANT_Module:
+            case CONSTANT_Package:
+                return 2;
+            case CONSTANT_MethodHandle:
+                return 3;
+            default:
+                return 0;
+        }
+    }
+
+    bool equals(const char* value, u16 len) {
+        return _tag == CONSTANT_Utf8 && info() == len && memcmp(_info + 2, value, len) == 0;
+    }
+
+    bool matches(const char* value, u16 len) {
+        if (len > 0 && value[len - 1] == '*') {
+            return _tag == CONSTANT_Utf8 && info() >= len - 1 && memcmp(_info + 2, value, len - 1) == 0;
+        }
+        return equals(value, len);
+    }
+};
+
+enum Scope {
+    SCOPE_CLASS,
+    SCOPE_FIELD,
+    SCOPE_METHOD,
+    SCOPE_REWRITE_METHOD,
+    SCOPE_REWRITE_CODE
+};
+
+enum PatchConstants {
+    EXTRA_CONSTANTS = 6,
+    EXTRA_BYTECODES = 4,
+    EXTRA_STACKMAPS = 1
+};
+
+
+class BytecodeRewriter {
+  private:
+    const u8* _src;
+    const u8* _src_limit;
+
+    u8* _dst;
+    int _dst_len;
+    int _dst_capacity;
+
+    Constant** _cpool;
+    u16 _cpool_len;
+
+    const char* _target_class;
+    u16 _target_class_len;
+    const char* _target_method;
+    u16 _target_method_len;
+    const char* _target_signature;
+    u16 _target_signature_len;
+
+    // Reader
+
+    const u8* get(int bytes) {
+        const u8* result = _src;
+        _src += bytes;
+        return _src <= _src_limit ? result : NULL;
+    }
+
+    u8 get8() {
+        return *get(1);
+    }
+
+    u16 get16() {
+        return ntohs(*(u16*)get(2));
+    }
+
+    u32 get32() {
+        return ntohl(*(u32*)get(4));
+    }
+
+    u64 get64() {
+        return OS::ntoh64(*(u64*)get(8));
+    }
+
+    Constant* getConstant() {
+        Constant* c = (Constant*)get(1);
+        get(c->length());
+        return c;
+    }
+
+    // Writer
+
+    u8* alloc(int bytes) {
+        if (_dst_len + bytes > _dst_capacity) {
+            grow(_dst_len + bytes + 2000);
+        }
+        u8* result = _dst + _dst_len;
+        _dst_len += bytes;
+        return result;
+    }
+
+    void grow(int new_capacity) {
+        u8* new_dst = NULL;
+        VM::jvmti()->Allocate(new_capacity, &new_dst);
+        memcpy(new_dst, _dst, _dst_len);
+        VM::jvmti()->Deallocate(_dst);
+
+        _dst = new_dst;
+        _dst_capacity = new_capacity;
+    }
+
+    void put(const u8* src, int bytes) {
+        memcpy(alloc(bytes), src, bytes);
+    }
+
+    void put8(u8 v) {
+        *alloc(1) = v;
+    }
+
+    void put16(u16 v) {
+        *(u16*)alloc(2) = htons(v);
+    }
+
+    void put32(u32 v) {
+        *(u32*)alloc(4) = htonl(v);
+    }
+
+    void put64(u64 v) {
+        *(u64*)alloc(8) = OS::hton64(v);
+    }
+
+    void putConstant(const char* value) {
+        u16 len = strlen(value);
+        put8(CONSTANT_Utf8);
+        put16(len);
+        put((const u8*)value, len);
+    }
+
+    void putConstant(u8 tag, u16 ref) {
+        put8(tag);
+        put16(ref);
+    }
+
+    void putConstant(u8 tag, u16 ref1, u16 ref2) {
+        put8(tag);
+        put16(ref1);
+        put16(ref2);
+    }
+
+    // BytecodeRewriter
+
+    void rewriteCode();
+    void rewriteBytecodeTable(int data_len);
+    void rewriteStackMapTable();
+    void rewriteAttributes(Scope scope);
+    void rewriteMembers(Scope scope);
+    bool rewriteClass();
+
+  public:
+    BytecodeRewriter(const u8* class_data, int class_data_len, const char* target_class) :
+        _src(class_data),
+        _src_limit(class_data + class_data_len),
+        _dst(NULL),
+        _dst_len(0),
+        _dst_capacity(class_data_len + 400),
+        _cpool(NULL) {
+
+        _target_class = target_class;
+        _target_class_len = strlen(_target_class);
+
+        _target_method = _target_class + _target_class_len + 1;
+        _target_signature = strchr(_target_method, '(');
+
+        if (_target_signature == NULL) {
+            _target_method_len = strlen(_target_method);
+        } else {
+            _target_method_len = _target_signature - _target_method;
+            _target_signature_len = strlen(_target_signature);
+        }
+    }
+
+    ~BytecodeRewriter() {
+        delete[] _cpool;
+    }
+
+    void rewrite(u8** new_class_data, int* new_class_data_len) {
+        if (VM::jvmti()->Allocate(_dst_capacity, &_dst) == 0) {
+            if (rewriteClass()) {
+                *new_class_data = _dst;
+                *new_class_data_len = _dst_len;
+            } else {
+                VM::jvmti()->Deallocate(_dst);
+            }
+        }
+    }
+};
+
+
+void BytecodeRewriter::rewriteCode() {
+    u32 attribute_length = get32();
+    put32(attribute_length);
+
+    int code_begin = _dst_len;
+
+    u16 max_stack = get16();
+    put16(max_stack);
+
+    u16 max_locals = get16();
+    put16(max_locals);
+
+    u32 code_length = get32();
+    put32(code_length + EXTRA_BYTECODES);
+
+    // invokestatic "one/profiler/Instrument.recordSample()V"
+    // nop after invoke helps to prepend StackMapTable without rewriting
+    put8(0xb8);
+    put16(_cpool_len);
+    put8(0);
+    // The rest of the code is unchanged
+    put(get(code_length), code_length);
+
+    u16 exception_table_length = get16();
+    put16(exception_table_length);
+
+    for (int i = 0; i < exception_table_length; i++) {
+        u16 start_pc = get16();
+        u16 end_pc = get16();
+        u16 handler_pc = get16();
+        u16 catch_type = get16();
+        put16(EXTRA_BYTECODES + start_pc);
+        put16(EXTRA_BYTECODES + end_pc);
+        put16(EXTRA_BYTECODES + handler_pc);
+        put16(catch_type);
+    }
+
+    rewriteAttributes(SCOPE_REWRITE_CODE);
+
+    // Patch attribute length
+    *(u32*)(_dst + code_begin - 4) = htonl(_dst_len - code_begin);
+}
+
+void BytecodeRewriter::rewriteBytecodeTable(int data_len) {
+    u32 attribute_length = get32();
+    put32(attribute_length);
+
+    u16 table_length = get16();
+    put16(table_length);
+
+    for (int i = 0; i < table_length; i++) {
+        u16 start_pc = get16();
+        put16(EXTRA_BYTECODES + start_pc);
+
+        put(get(data_len), data_len);
+    }
+}
+
+void BytecodeRewriter::rewriteStackMapTable() {
+    u32 attribute_length = get32();
+    put32(attribute_length + EXTRA_STACKMAPS);
+
+    u16 number_of_entries = get16();
+    put16(number_of_entries + EXTRA_STACKMAPS);
+
+    // Prepend same_frame
+    put8(EXTRA_BYTECODES - 1);
+    put(get(attribute_length - 2), attribute_length - 2);
+}
+
+void BytecodeRewriter::rewriteAttributes(Scope scope) {
+    u16 attributes_count = get16();
+    put16(attributes_count);
+
+    for (int i = 0; i < attributes_count; i++) {
+        u16 attribute_name_index = get16();
+        put16(attribute_name_index);
+
+        Constant* attribute_name = _cpool[attribute_name_index];
+        if (scope == SCOPE_REWRITE_METHOD && attribute_name->equals("Code", 4)) {
+            rewriteCode();
+            continue;
+        } else if (scope == SCOPE_REWRITE_CODE) {
+            if (attribute_name->equals("LineNumberTable", 15)) {
+                rewriteBytecodeTable(2);
+                continue;
+            } else if (attribute_name->equals("LocalVariableTable", 18) ||
+                       attribute_name->equals("LocalVariableTypeTable", 22)) {
+                rewriteBytecodeTable(8);
+                continue;
+            } else if (attribute_name->equals("StackMapTable", 13)) {
+                rewriteStackMapTable();
+                continue;
+            }
+        }
+
+        u32 attribute_length = get32();
+        put32(attribute_length);
+        put(get(attribute_length), attribute_length);
+    }
+}
+
+void BytecodeRewriter::rewriteMembers(Scope scope) {
+    u16 members_count = get16();
+    put16(members_count);
+
+    for (int i = 0; i < members_count; i++) {
+        u16 access_flags = get16();
+        put16(access_flags);
+
+        u16 name_index = get16();
+        put16(name_index);
+
+        u16 descriptor_index = get16();
+        put16(descriptor_index);
+
+        bool need_rewrite = scope == SCOPE_METHOD
+            && _cpool[name_index]->matches(_target_method, _target_method_len)
+            && (_target_signature == NULL || _cpool[descriptor_index]->matches(_target_signature, _target_signature_len));
+
+        rewriteAttributes(need_rewrite ? SCOPE_REWRITE_METHOD : SCOPE_METHOD);
+    }
+}
+
+bool BytecodeRewriter::rewriteClass() {
+    u32 magic = get32();
+    put32(magic);
+
+    u32 version = get32();
+    put32(version);
+
+    _cpool_len = get16();
+    put16(_cpool_len + EXTRA_CONSTANTS);
+
+    const u8* cpool_start = _src;
+
+    _cpool = new Constant*[_cpool_len];
+    for (int i = 1; i < _cpool_len; i += _cpool[i]->slots()) {
+        _cpool[i] = getConstant();
+    }
+
+    const u8* cpool_end = _src;
+    put(cpool_start, cpool_end - cpool_start);
+
+    putConstant(CONSTANT_Methodref, _cpool_len + 1, _cpool_len + 2);
+    putConstant(CONSTANT_Class, _cpool_len + 3);
+    putConstant(CONSTANT_NameAndType, _cpool_len + 4, _cpool_len + 5);
+    putConstant("one/profiler/Instrument");
+    putConstant("recordSample");
+    putConstant("()V");
+
+    u16 access_flags = get16();
+    put16(access_flags);
+
+    u16 this_class = get16();
+    put16(this_class);
+
+    u16 class_name_index = _cpool[this_class]->info();
+    if (!_cpool[class_name_index]->equals(_target_class, _target_class_len)) {
+        return false;
+    }
+
+    u16 super_class = get16();
+    put16(super_class);
+
+    u16 interfaces_count = get16();
+    put16(interfaces_count);
+    put(get(interfaces_count * 2), interfaces_count * 2);
+
+    rewriteMembers(SCOPE_FIELD);
+    rewriteMembers(SCOPE_METHOD);
+    rewriteAttributes(SCOPE_CLASS);
+
+    return true;
+}
+
+
+char* Instrument::_target_class = NULL;
+bool Instrument::_instrument_class_loaded = false;
+u64 Instrument::_interval;
+volatile u64 Instrument::_calls;
+volatile bool Instrument::_running;
+
+Error Instrument::check(Arguments& args) {
+    if (!_instrument_class_loaded) {
+        JNIEnv* jni = VM::jni();
+        const JNINativeMethod native_method = {(char*)"recordSample", (char*)"()V", (void*)recordSample};
+
+        jclass cls = jni->DefineClass(NULL, NULL, (const jbyte*)INSTRUMENT_CLASS, sizeof(INSTRUMENT_CLASS));
+        if (cls == NULL || jni->RegisterNatives(cls, &native_method, 1) != 0) {
+            jni->ExceptionClear();
+            return Error("Could not load Instrument class");
+        }
+
+        _instrument_class_loaded = true;
+    }
+
+    return Error::OK;
+}
+
+Error Instrument::start(Arguments& args) {
+    Error error = check(args);
+    if (error) {
+        return error;
+    }
+
+    if (args._interval < 0) {
+        return Error("interval must be positive");
+    }
+
+    setupTargetClassAndMethod(args._event_desc);
+    _interval = args._interval ? args._interval : 1;
+    _calls = 0;
+    _running = true;
+
+    jvmtiEnv* jvmti = VM::jvmti();
+    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, NULL);
+    retransformMatchedClasses(jvmti);
+
+    return Error::OK;
+}
+
+void Instrument::stop() {
+    _running = false;
+
+    jvmtiEnv* jvmti = VM::jvmti();
+    retransformMatchedClasses(jvmti);  // undo transformation
+    jvmti->SetEventNotificationMode(JVMTI_DISABLE, JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, NULL);
+}
+
+void Instrument::setupTargetClassAndMethod(const char* event) {
+    char* new_class = strdup(event);
+    *strrchr(new_class, '.') = 0;
+
+    for (char* s = new_class; *s; s++) {
+        if (*s == '.') *s = '/';
+    }
+
+    char* old_class = _target_class;
+    _target_class = new_class;
+    free(old_class);
+}
+
+void Instrument::retransformMatchedClasses(jvmtiEnv* jvmti) {
+    jint class_count;
+    jclass* classes;
+    if (jvmti->GetLoadedClasses(&class_count, &classes) != 0) {
+        return;
+    }
+
+    jint matched_count = 0;
+    size_t len = strlen(_target_class);
+    for (int i = 0; i < class_count; i++) {
+        char* signature;
+        if (jvmti->GetClassSignature(classes[i], &signature, NULL) == 0) {
+            if (signature[0] == 'L' && strncmp(signature + 1, _target_class, len) == 0 && signature[len + 1] == ';') {
+                classes[matched_count++] = classes[i];
+            }
+            jvmti->Deallocate((unsigned char*)signature);
+        }
+    }
+
+    if (matched_count > 0) {
+        jvmti->RetransformClasses(matched_count, classes);
+        VM::jni()->ExceptionClear();
+    }
+
+    jvmti->Deallocate((unsigned char*)classes);
+}
+
+void JNICALL Instrument::ClassFileLoadHook(jvmtiEnv* jvmti, JNIEnv* jni,
+                                           jclass class_being_redefined, jobject loader,
+                                           const char* name, jobject protection_domain,
+                                           jint class_data_len, const u8* class_data,
+                                           jint* new_class_data_len, u8** new_class_data) {
+    // Do not retransform if the profiling has stopped
+    if (!_running) return;
+
+    if (name == NULL || strcmp(name, _target_class) == 0) {
+        BytecodeRewriter rewriter(class_data, class_data_len, _target_class);
+        rewriter.rewrite(new_class_data, new_class_data_len);
+    }
+}
+
+void JNICALL Instrument::recordSample(JNIEnv* jni, jobject unused) {
+    if (!_enabled) return;
+
+    if (_interval <= 1 || ((atomicInc(_calls) + 1) % _interval) == 0) {
+        ExecutionEvent event;
+        Profiler::_instance.recordSample(NULL, _interval, BCI_INSTRUMENT, &event);
+    }
+}

src/instrument.h

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2019 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _INSTRUMENT_H
+#define _INSTRUMENT_H
+
+#include <jvmti.h>
+#include "engine.h"
+
+
+class Instrument : public Engine {
+  private:
+    static char* _target_class;
+    static bool _instrument_class_loaded;
+    static u64 _interval;
+    static volatile u64 _calls;
+    static volatile bool _running;
+
+  public:
+    const char* name() {
+        return "instrument";
+    }
+
+    const char* units() {
+        return "calls";
+    }
+
+    CStack cstack() {
+        return CSTACK_NO;
+    }
+
+    Error check(Arguments& args);
+    Error start(Arguments& args);
+    void stop();
+
+    void setupTargetClassAndMethod(const char* event);
+
+    void retransformMatchedClasses(jvmtiEnv* jvmti);
+
+    static void JNICALL ClassFileLoadHook(jvmtiEnv* jvmti, JNIEnv* jni,
+                                          jclass class_being_redefined, jobject loader,
+                                          const char* name, jobject protection_domain,
+                                          jint class_data_len, const u8* class_data,
+                                          jint* new_class_data_len, u8** new_class_data);
+
+    static void JNICALL recordSample(JNIEnv* jni, jobject unused);
+};
+
+#endif // _INSTRUMENT_H

src/itimer.cpp

@@ -24,7 +24,24 @@ long ITimer::_interval;
 
 
 void ITimer::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {
-    Profiler::_instance.recordSample(ucontext, _interval, 0, NULL);
+    if (!_enabled) return;
+
+    ExecutionEvent event;
+    Profiler::_instance.recordSample(ucontext, _interval, 0, &event);
+}
+
+Error ITimer::check(Arguments& args) {
+    OS::installSignalHandler(SIGPROF, NULL, SIG_IGN);
+
+    struct itimerval tv_on = {{1, 0}, {1, 0}};
+    if (setitimer(ITIMER_PROF, &tv_on, NULL) != 0) {
+        return Error("ITIMER_PROF is not supported on this system");
+    }
+
+    struct itimerval tv_off = {{0, 0}, {0, 0}};
+    setitimer(ITIMER_PROF, &tv_off, NULL);
+
+    return Error::OK;
 }
 
 Error ITimer::start(Arguments& args) {
@@ -38,7 +55,10 @@ Error ITimer::start(Arguments& args) {
     long sec = _interval / 1000000000;
     long usec = (_interval % 1000000000) / 1000;
     struct itimerval tv = {{sec, usec}, {sec, usec}};
-    setitimer(ITIMER_PROF, &tv, NULL);
+    
+    if (setitimer(ITIMER_PROF, &tv, NULL) != 0) {
+        return Error("ITIMER_PROF is not supported on this system");
+    }
 
     return Error::OK;
 }

src/itimer.h

@@ -36,6 +36,7 @@ class ITimer : public Engine {
         return "ns";
     }
 
+    Error check(Arguments& args);
     Error start(Arguments& args);
     void stop();
 };

src/javaApi.cpp

@@ -18,28 +18,24 @@
 #include <sstream>
 #include <errno.h>
 #include <string.h>
+#include "javaApi.h"
 #include "arguments.h"
+#include "os.h"
 #include "profiler.h"
-
-
-static void throw_new(JNIEnv* env, const char* exception_class, const char* message) {
-    jclass cls = env->FindClass(exception_class);
-    if (cls != NULL) {
-        env->ThrowNew(cls, message);
-    }
-}
+#include "vmStructs.h"
 
 
 extern "C" JNIEXPORT void JNICALL
 Java_one_profiler_AsyncProfiler_start0(JNIEnv* env, jobject unused, jstring event, jlong interval, jboolean reset) {
     Arguments args;
-    args._event = env->GetStringUTFChars(event, NULL);
+    const char* event_str = env->GetStringUTFChars(event, NULL);
+    args.addEvent(event_str); 
     args._interval = interval;
     Error error = Profiler::_instance.start(args, reset);
-    env->ReleaseStringUTFChars(event, args._event);
+    env->ReleaseStringUTFChars(event, event_str);
 
     if (error) {
-        throw_new(env, "java/lang/IllegalStateException", error.message());
+        JavaAPI::throwNew(env, "java/lang/IllegalStateException", error.message());
     }
 }
 
@@ -48,15 +44,10 @@ Java_one_profiler_AsyncProfiler_stop0(JNIEnv* env, jobject unused) {
     Error error = Profiler::_instance.stop();
 
     if (error) {
-        throw_new(env, "java/lang/IllegalStateException", error.message());
+        JavaAPI::throwNew(env, "java/lang/IllegalStateException", error.message());
     }
 }
 
-extern "C" JNIEXPORT jlong JNICALL
-Java_one_profiler_AsyncProfiler_getSamples(JNIEnv* env, jobject unused) {
-    return (jlong)Profiler::_instance.total_samples();
-}
-
 extern "C" JNIEXPORT jstring JNICALL
 Java_one_profiler_AsyncProfiler_execute0(JNIEnv* env, jobject unused, jstring command) {
     Arguments args;
@@ -65,7 +56,7 @@ Java_one_profiler_AsyncProfiler_execute0(JNIEnv* env, jobject unused, jstring co
     env->ReleaseStringUTFChars(command, command_str);
 
     if (error) {
-        throw_new(env, "java/lang/IllegalArgumentException", error.message());
+        JavaAPI::throwNew(env, "java/lang/IllegalArgumentException", error.message());
         return NULL;
     }
 
@@ -80,45 +71,87 @@ Java_one_profiler_AsyncProfiler_execute0(JNIEnv* env, jobject unused, jstring co
             out.close();
             return env->NewStringUTF("OK");
         } else {
-            throw_new(env, "java/io/IOException", strerror(errno));
+            JavaAPI::throwNew(env, "java/io/IOException", strerror(errno));
             return NULL;
         }
     }
 }
 
-extern "C" JNIEXPORT jstring JNICALL
-Java_one_profiler_AsyncProfiler_dumpCollapsed0(JNIEnv* env, jobject unused, jint counter) {
-    Arguments args;
-    args._counter = counter == COUNTER_SAMPLES ? COUNTER_SAMPLES : COUNTER_TOTAL;
-
-    std::ostringstream out;
-    Profiler::_instance.dumpCollapsed(out, args);
-    return env->NewStringUTF(out.str().c_str());
+extern "C" JNIEXPORT jlong JNICALL
+Java_one_profiler_AsyncProfiler_getSamples(JNIEnv* env, jobject unused) {
+    return (jlong)Profiler::_instance.total_samples();
 }
 
-extern "C" JNIEXPORT jstring JNICALL
-Java_one_profiler_AsyncProfiler_dumpTraces0(JNIEnv* env, jobject unused, jint max_traces) {
-    Arguments args;
-    args._dump_traces = max_traces ? max_traces : MAX_CALLTRACES;
+extern "C" JNIEXPORT void JNICALL
+Java_one_profiler_AsyncProfiler_filterThread0(JNIEnv* env, jobject unused, jthread thread, jboolean enable) {
+    int thread_id;
+    if (thread == NULL) {
+        thread_id = OS::threadId();
+    } else if (VMThread::hasNativeId()) {
+        VMThread* vmThread = VMThread::fromJavaThread(env, thread);
+        if (vmThread == NULL) {
+            return;
+        }
+        thread_id = vmThread->osThreadId();
+    } else {
+        return;
+    }
 
-    std::ostringstream out;
-    Profiler::_instance.dumpSummary(out);
-    Profiler::_instance.dumpTraces(out, args);
-    return env->NewStringUTF(out.str().c_str());
+    ThreadFilter* thread_filter = Profiler::_instance.threadFilter();
+    if (enable) {
+        thread_filter->add(thread_id);
+    } else {
+        thread_filter->remove(thread_id);
+    }
 }
 
-extern "C" JNIEXPORT jstring JNICALL
-Java_one_profiler_AsyncProfiler_dumpFlat0(JNIEnv* env, jobject unused, jint max_methods) {
-    Arguments args;
-    args._dump_flat = max_methods ? max_methods : MAX_CALLTRACES;
 
-    std::ostringstream out;
-    Profiler::_instance.dumpSummary(out);
-    Profiler::_instance.dumpFlat(out, args);
-    return env->NewStringUTF(out.str().c_str());
+#define F(name, sig)  {(char*)#name, (char*)sig, (void*)Java_one_profiler_AsyncProfiler_##name}
+
+static const JNINativeMethod profiler_natives[] = {
+    F(start0,        "(Ljava/lang/String;JZ)V"),
+    F(stop0,         "()V"),
+    F(execute0,      "(Ljava/lang/String;)Ljava/lang/String;"),
+    F(getSamples,    "()J"),
+    F(filterThread0, "(Ljava/lang/Thread;Z)V"),
+};
+
+#undef F
+
+
+void JavaAPI::throwNew(JNIEnv* env, const char* exception_class, const char* message) {
+    jclass cls = env->FindClass(exception_class);
+    if (cls != NULL) {
+        env->ThrowNew(cls, message);
+    }
 }
 
-extern "C" JNIEXPORT jstring JNICALL
-Java_one_profiler_AsyncProfiler_version0(JNIEnv* env, jobject unused) {
-    return env->NewStringUTF(PROFILER_VERSION);
+// Since AsyncProfiler class can be renamed or moved to another package (shaded),
+// we look for the actual class in the stack trace.
+void JavaAPI::registerNatives(jvmtiEnv* jvmti, JNIEnv* jni) {
+    jvmtiFrameInfo frame[10];
+    jint frame_count;
+    if (jvmti->GetStackTrace(NULL, 0, sizeof(frame) / sizeof(frame[0]), frame, &frame_count) != 0) {
+        return;
+    }
+
+    jclass System = jni->FindClass("java/lang/System");
+    jmethodID load = jni->GetStaticMethodID(System, "load", "(Ljava/lang/String;)V");
+    jmethodID loadLibrary = jni->GetStaticMethodID(System, "loadLibrary", "(Ljava/lang/String;)V");
+
+    // Look for System.load() or System.loadLibrary() method in the stack trace.
+    // The next frame will belong to AsyncProfiler class.
+    for (int i = 0; i < frame_count - 1; i++) {
+        if (frame[i].method == load || frame[i].method == loadLibrary) {
+            jclass profiler_class;
+            if (jvmti->GetMethodDeclaringClass(frame[i + 1].method, &profiler_class) == 0) {
+                for (int j = 0; j < sizeof(profiler_natives) / sizeof(JNINativeMethod); j++) {
+                    jni->RegisterNatives(profiler_class, &profiler_natives[j], 1);
+                }
+            }
+            break;
+        }
+    }
+
+    jni->ExceptionClear();
 }

src/javaApi.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _JAVAAPI_H
+#define _JAVAAPI_H
+
+#include <jvmti.h>
+
+
+class JavaAPI {
+  public:
+    static void throwNew(JNIEnv* env, const char* exception_class, const char* message);
+    static void registerNatives(jvmtiEnv* jvmti, JNIEnv* jni);
+};
+
+#endif // _JAVAAPI_H

src/jfrMetadata.cpp

@@ -0,0 +1,213 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "jfrMetadata.h"
+
+
+std::map<std::string, int> Element::_string_map;
+std::vector<std::string> Element::_strings;
+
+JfrMetadata JfrMetadata::_root;
+
+JfrMetadata::JfrMetadata() : Element("root") {
+    *this
+        << (element("metadata")
+
+            << type("boolean", T_BOOLEAN)
+            << type("char", T_CHAR)
+            << type("float", T_FLOAT)
+            << type("double", T_DOUBLE)
+            << type("byte", T_BYTE)
+            << type("short", T_SHORT)
+            << type("int", T_INT)
+            << type("long", T_LONG)
+
+            << type("java.lang.String", T_STRING)
+
+            << (type("java.lang.Class", T_CLASS, "Java Class")
+                << field("classLoader", T_CLASS_LOADER, "Class Loader", F_CPOOL)
+                << field("name", T_SYMBOL, "Name", F_CPOOL)
+                << field("package", T_PACKAGE, "Package", F_CPOOL)
+                << field("modifiers", T_INT, "Access Modifiers"))
+
+            << (type("java.lang.Thread", T_THREAD, "Thread")
+                << field("osName", T_STRING, "OS Thread Name")
+                << field("osThreadId", T_LONG, "OS Thread Id")
+                << field("javaName", T_STRING, "Java Thread Name")
+                << field("javaThreadId", T_LONG, "Java Thread Id"))
+
+            << (type("jdk.types.ClassLoader", T_CLASS_LOADER, "Java Class Loader")
+                << field("type", T_CLASS, "Type", F_CPOOL)
+                << field("name", T_SYMBOL, "Name", F_CPOOL))
+
+            << (type("jdk.types.FrameType", T_FRAME_TYPE, "Frame type", true)
+                << field("description", T_STRING, "Description"))
+
+            << (type("jdk.types.ThreadState", T_THREAD_STATE, "Java Thread State", true)
+                << field("name", T_STRING, "Name"))
+
+            << (type("jdk.types.StackTrace", T_STACK_TRACE, "Stacktrace")
+                << field("truncated", T_BOOLEAN, "Truncated")
+                << field("frames", T_STACK_FRAME, "Stack Frames", F_ARRAY))
+
+            << (type("jdk.types.StackFrame", T_STACK_FRAME)
+                << field("method", T_METHOD, "Java Method", F_CPOOL)
+                << field("lineNumber", T_INT, "Line Number")
+                << field("bytecodeIndex", T_INT, "Bytecode Index")
+                << field("type", T_FRAME_TYPE, "Frame Type", F_CPOOL))
+
+            << (type("jdk.types.Method", T_METHOD, "Java Method")
+                << field("type", T_CLASS, "Type", F_CPOOL)
+                << field("name", T_SYMBOL, "Name", F_CPOOL)
+                << field("descriptor", T_SYMBOL, "Descriptor", F_CPOOL)
+                << field("modifiers", T_INT, "Access Modifiers")
+                << field("hidden", T_BOOLEAN, "Hidden"))
+
+            << (type("jdk.types.Package", T_PACKAGE, "Package")
+                << field("name", T_SYMBOL, "Name", F_CPOOL))
+
+            << (type("jdk.types.Symbol", T_SYMBOL, "Symbol", true)
+                << field("string", T_STRING, "String"))
+
+            << (type("jdk.ExecutionSample", T_EXECUTION_SAMPLE, "Method Profiling Sample")
+                << category("Java Virtual Machine", "Profiling")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("sampledThread", T_THREAD, "Thread", F_CPOOL)
+                << field("stackTrace", T_STACK_TRACE, "Stack Trace", F_CPOOL)
+                << field("state", T_THREAD_STATE, "Thread State", F_CPOOL))
+
+            << (type("jdk.ObjectAllocationInNewTLAB", T_ALLOC_IN_NEW_TLAB, "Allocation in new TLAB")
+                << category("Java Application")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("eventThread", T_THREAD, "Event Thread", F_CPOOL)
+                << field("stackTrace", T_STACK_TRACE, "Stack Trace", F_CPOOL)
+                << field("objectClass", T_CLASS, "Object Class", F_CPOOL)
+                << field("allocationSize", T_LONG, "Allocation Size", F_BYTES)
+                << field("tlabSize", T_LONG, "TLAB Size", F_BYTES))
+
+            << (type("jdk.ObjectAllocationOutsideTLAB", T_ALLOC_OUTSIDE_TLAB, "Allocation outside TLAB")
+                << category("Java Application")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("eventThread", T_THREAD, "Event Thread", F_CPOOL)
+                << field("stackTrace", T_STACK_TRACE, "Stack Trace", F_CPOOL)
+                << field("objectClass", T_CLASS, "Object Class", F_CPOOL)
+                << field("allocationSize", T_LONG, "Allocation Size", F_BYTES))
+
+            << (type("jdk.JavaMonitorEnter", T_MONITOR_ENTER, "Java Monitor Blocked")
+                << category("Java Application")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("duration", T_LONG, "Duration", F_DURATION_TICKS)
+                << field("eventThread", T_THREAD, "Event Thread", F_CPOOL)
+                << field("stackTrace", T_STACK_TRACE, "Stack Trace", F_CPOOL)
+                << field("monitorClass", T_CLASS, "Monitor Class", F_CPOOL)
+                << field("address", T_LONG, "Monitor Address", F_ADDRESS))
+
+            << (type("jdk.ThreadPark", T_THREAD_PARK, "Java Thread Park")
+                << category("Java Application")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("duration", T_LONG, "Duration", F_DURATION_TICKS)
+                << field("eventThread", T_THREAD, "Event Thread", F_CPOOL)
+                << field("stackTrace", T_STACK_TRACE, "Stack Trace", F_CPOOL)
+                << field("parkedClass", T_CLASS, "Class Parked On", F_CPOOL)
+                << field("timeout", T_LONG, "Park Timeout", F_DURATION_NANOS)
+                << field("address", T_LONG, "Address of Object Parked", F_ADDRESS))
+
+            << (type("jdk.CPULoad", T_CPU_LOAD, "CPU Load")
+                << category("Operating System", "Processor")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("jvmUser", T_FLOAT, "JVM User", F_PERCENTAGE)
+                << field("jvmSystem", T_FLOAT, "JVM System", F_PERCENTAGE)
+                << field("machineTotal", T_FLOAT, "Machine Total", F_PERCENTAGE))
+
+            << (type("jdk.ActiveRecording", T_ACTIVE_RECORDING, "Flight Recording")
+                << category("Flight Recorder")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("duration", T_LONG, "Duration", F_DURATION_TICKS)
+                << field("eventThread", T_THREAD, "Event Thread", F_CPOOL)
+                << field("id", T_LONG, "Id")
+                << field("name", T_STRING, "Name")
+                << field("destination", T_STRING, "Destination")
+                << field("maxAge", T_LONG, "Max Age", F_DURATION_MILLIS)
+                << field("maxSize", T_LONG, "Max Size", F_BYTES)
+                << field("recordingStart", T_LONG, "Start Time", F_TIME_MILLIS)
+                << field("recordingDuration", T_LONG, "Recording Duration", F_DURATION_MILLIS))
+
+            << (type("jdk.ActiveSetting", T_ACTIVE_SETTING, "Recording Setting")
+                << category("Flight Recorder")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("duration", T_LONG, "Duration", F_DURATION_TICKS)
+                << field("eventThread", T_THREAD, "Event Thread", F_CPOOL)
+                << field("id", T_LONG, "Event Id")
+                << field("name", T_STRING, "Setting Name")
+                << field("value", T_STRING, "Setting Value"))
+
+            << (type("jdk.OSInformation", T_OS_INFORMATION, "OS Information")
+                << category("Operating System")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("osVersion", T_STRING, "OS Version"))
+
+            << (type("jdk.CPUInformation", T_CPU_INFORMATION, "CPU Information")
+                << category("Operating System", "Processor")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("cpu", T_STRING, "Type")
+                << field("description", T_STRING, "Description")
+                << field("sockets", T_INT, "Sockets", F_UNSIGNED)
+                << field("cores", T_INT, "Cores", F_UNSIGNED)
+                << field("hwThreads", T_INT, "Hardware Threads", F_UNSIGNED))
+
+            << (type("jdk.JVMInformation", T_JVM_INFORMATION, "JVM Information")
+                << category("Java Virtual Machine")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("jvmName", T_STRING, "JVM Name")
+                << field("jvmVersion", T_STRING, "JVM Version")
+                << field("jvmArguments", T_STRING, "JVM Command Line Arguments")
+                << field("jvmFlags", T_STRING, "JVM Settings File Arguments")
+                << field("javaArguments", T_STRING, "Java Application Arguments")
+                << field("jvmStartTime", T_LONG, "JVM Start Time", F_TIME_MILLIS)
+                << field("pid", T_LONG, "Process Identifier"))
+
+            << (type("jdk.InitialSystemProperty", T_INITIAL_SYSTEM_PROPERTY, "Initial System Property")
+                << category("Java Virtual Machine")
+                << field("startTime", T_LONG, "Start Time", F_TIME_TICKS)
+                << field("key", T_STRING, "Key")
+                << field("value", T_STRING, "Value"))
+
+            << (type("jdk.jfr.Label", T_LABEL, NULL)
+                << field("value", T_STRING))
+
+            << (type("jdk.jfr.Category", T_CATEGORY, NULL)
+                << field("value", T_STRING, NULL, F_ARRAY))
+
+            << (type("jdk.jfr.Timestamp", T_TIMESTAMP, "Timestamp")
+                << field("value", T_STRING))
+
+            << (type("jdk.jfr.Timespan", T_TIMESPAN, "Timespan")
+                << field("value", T_STRING))
+
+            << (type("jdk.jfr.DataAmount", T_DATA_AMOUNT, "Data Amount")
+                << field("value", T_STRING))
+
+            << type("jdk.jfr.MemoryAddress", T_MEMORY_ADDRESS, "Memory Address")
+
+            << type("jdk.jfr.Unsigned", T_UNSIGNED, "Unsigned Value")
+
+            << type("jdk.jfr.Percentage", T_PERCENTAGE, "Percentage"))
+
+        << element("region").attribute("locale", "en_US").attribute("gmtOffset", "0");
+
+    // The map is used only during construction
+    _string_map.clear();
+}

src/jfrMetadata.h

@@ -0,0 +1,231 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _JFRMETADATA_H
+#define _JFRMETADATA_H
+
+#include <string>
+#include <map>
+#include <vector>
+#include <stdio.h>
+#include <string.h>
+
+
+enum JfrType {
+    T_METADATA = 0,
+    T_CPOOL = 1,
+
+    T_BOOLEAN = 4,
+    T_CHAR = 5,
+    T_FLOAT = 6,
+    T_DOUBLE = 7,
+    T_BYTE = 8,
+    T_SHORT = 9,
+    T_INT = 10,
+    T_LONG = 11,
+
+    T_STRING = 20,
+    T_CLASS = 21,
+    T_THREAD = 22,
+    T_CLASS_LOADER = 23,
+    T_FRAME_TYPE = 24,
+    T_THREAD_STATE = 25,
+    T_STACK_TRACE = 26,
+    T_STACK_FRAME = 27,
+    T_METHOD = 28,
+    T_PACKAGE = 29,
+    T_SYMBOL = 30,
+
+    T_EVENT = 100,
+    T_EXECUTION_SAMPLE = 101,
+    T_ALLOC_IN_NEW_TLAB = 102,
+    T_ALLOC_OUTSIDE_TLAB = 103,
+    T_MONITOR_ENTER = 104,
+    T_THREAD_PARK = 105,
+    T_CPU_LOAD = 106,
+    T_ACTIVE_RECORDING = 107,
+    T_ACTIVE_SETTING = 108,
+    T_OS_INFORMATION = 109,
+    T_CPU_INFORMATION = 110,
+    T_JVM_INFORMATION = 111,
+    T_INITIAL_SYSTEM_PROPERTY = 112,
+
+    T_ANNOTATION = 200,
+    T_LABEL = 201,
+    T_CATEGORY = 202,
+    T_TIMESTAMP = 203,
+    T_TIMESPAN = 204,
+    T_DATA_AMOUNT = 205,
+    T_MEMORY_ADDRESS = 206,
+    T_UNSIGNED = 207,
+    T_PERCENTAGE = 208,
+};
+
+
+class Attribute {
+  public:
+    int _key;
+    int _value;
+
+    Attribute(int key, int value) : _key(key), _value(value) {
+    }
+};
+
+class Element {
+  protected:
+    static std::map<std::string, int> _string_map;
+    static std::vector<std::string> _strings;
+
+    static int getId(const char* s) {
+        std::string str(s);
+        int id = _string_map[str];
+        if (id == 0) {
+            id = _string_map[str] = _string_map.size();
+            _strings.push_back(str);
+        }
+        return id - 1;
+    }
+
+  public:
+    const int _name;
+    std::vector<Attribute> _attributes;
+    std::vector<const Element*> _children;
+
+    Element(const char* name) : _name(getId(name)), _attributes(), _children() {
+    }
+
+    Element& attribute(const char* key, const char* value) {
+        _attributes.push_back(Attribute(getId(key), getId(value)));
+        return *this;
+    }
+
+    Element& attribute(const char* key, JfrType value) {
+        char value_str[16];
+        sprintf(value_str, "%d", value);
+        return attribute(key, value_str);
+    }
+
+    Element& operator<<(const Element& child) {
+        _children.push_back(&child);
+        return *this;
+    }
+};
+
+class JfrMetadata : Element {
+  private:
+    static JfrMetadata _root;
+
+    enum FieldFlags {
+        F_CPOOL           = 0x1,
+        F_ARRAY           = 0x2,
+        F_UNSIGNED        = 0x4,
+        F_BYTES           = 0x8,
+        F_TIME_TICKS      = 0x10,
+        F_TIME_MILLIS     = 0x20,
+        F_DURATION_TICKS  = 0x40,
+        F_DURATION_NANOS  = 0x80,
+        F_DURATION_MILLIS = 0x100,
+        F_ADDRESS         = 0x200,
+        F_PERCENTAGE      = 0x400,
+    };
+
+    static Element& element(const char* name) {
+        return *new Element(name);
+    }
+
+    static Element& type(const char* name, JfrType id, const char* label = NULL, bool simple = false) {
+        Element& e = element("class");
+        e.attribute("name", name);
+        e.attribute("id", id);
+        if (simple) {
+            e.attribute("simpleType", "true");
+        } else if (id > T_ANNOTATION) {
+            e.attribute("superType", "java.lang.annotation.Annotation");
+        } else if (id > T_EVENT) {
+            e.attribute("superType", "jdk.jfr.Event");
+        }
+        if (label != NULL) {
+            e << annotation(T_LABEL, label);
+        }
+        return e;
+    }
+
+    static Element& field(const char* name, JfrType type, const char* label = NULL, int flags = 0) {
+        Element& e = element("field");
+        e.attribute("name", name);
+        e.attribute("class", type);
+        if (flags & F_CPOOL) {
+            e.attribute("constantPool", "true");
+        }
+        if (flags & F_ARRAY) {
+            e.attribute("dimension", "1");
+        }
+        if (label != NULL) {
+            e << annotation(T_LABEL, label);
+        }
+        if (flags & F_UNSIGNED) {
+            e << annotation(T_UNSIGNED);
+        } else if (flags & F_BYTES) {
+            e << annotation(T_UNSIGNED) << annotation(T_DATA_AMOUNT, "BYTES");
+        } else if (flags & F_TIME_TICKS) {
+            e << annotation(T_TIMESTAMP, "TICKS");
+        } else if (flags & F_TIME_MILLIS) {
+            e << annotation(T_TIMESTAMP, "MILLISECONDS_SINCE_EPOCH");
+        } else if (flags & F_DURATION_TICKS) {
+            e << annotation(T_TIMESPAN, "TICKS");
+        } else if (flags & F_DURATION_NANOS) {
+            e << annotation(T_TIMESPAN, "NANOSECONDS");
+        } else if (flags & F_DURATION_MILLIS) {
+            e << annotation(T_TIMESPAN, "MILLISECONDS");
+        } else if (flags & F_ADDRESS) {
+            e << annotation(T_UNSIGNED) << annotation(T_MEMORY_ADDRESS);
+        } else if (flags & F_PERCENTAGE) {
+            e << annotation(T_PERCENTAGE);
+        }
+        return e;
+    }
+
+    static Element& annotation(JfrType type, const char* value = NULL) {
+        Element& e = element("annotation");
+        e.attribute("class", type);
+        if (value != NULL) {
+            e.attribute("value", value);
+        }
+        return e;
+    }
+
+    static Element& category(const char* value0, const char* value1 = NULL) {
+        Element& e = annotation(T_CATEGORY);
+        e.attribute("value-0", value0);
+        if (value1 != NULL) {
+            e.attribute("value-1", value1);
+        }
+        return e;
+    }
+
+  public:
+    JfrMetadata();
+
+    static Element* root() {
+        return &_root;
+    }
+
+    static std::vector<std::string>& strings() {
+        return _strings;
+    }
+};
+
+#endif // _JFRMETADATA_H

src/jstack.cpp

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2021 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <signal.h>
+#include <time.h>
+#include "jstack.h"
+#include "profiler.h"
+
+
+// Wait at most this number of milliseconds to finish processing of pending signals
+const int MAX_WAIT_MILLIS = 2000;
+
+
+void JStack::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {
+    ExecutionEvent event;
+    event._thread_state = Profiler::_instance.getThreadState(ucontext);
+    Profiler::_instance.recordSample(ucontext, 1, 0, &event);
+}
+
+Error JStack::start(Arguments& args) {
+    OS::installSignalHandler(SIGVTALRM, signalHandler);
+
+    int self = OS::threadId();
+    u64 required_samples = Profiler::_instance.total_samples();
+    ThreadFilter* thread_filter = Profiler::_instance.threadFilter();
+    bool thread_filter_enabled = thread_filter->enabled();
+
+    ThreadList* thread_list = OS::listThreads();
+    int thread_id;
+    while ((thread_id = thread_list->next()) != -1) {
+        if (thread_id != self && (!thread_filter_enabled || thread_filter->accept(thread_id))) {
+            if (OS::sendSignalToThread(thread_id, SIGVTALRM)) {
+                required_samples++;
+            }
+        }
+    }
+    delete thread_list;
+
+    // Get our own stack trace after all other threads
+    if (!thread_filter_enabled || thread_filter->accept(self)) {
+        ExecutionEvent event;
+        event._thread_state = THREAD_RUNNING;
+        Profiler::_instance.recordSample(NULL, 1, 0, &event);
+        required_samples++;
+    }
+
+    // Wait until all asynchronous stack traces collected
+    for (int i = 0; Profiler::_instance.total_samples() < required_samples && i < MAX_WAIT_MILLIS; i++) {
+        struct timespec timeout = {0, 1000000};
+        nanosleep(&timeout, NULL);
+    }
+
+    return Error::OK;
+}
+
+void JStack::stop() {
+    // Nothing to do
+}

src/jstack.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2021 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _JSTACK_H
+#define _JSTACK_H
+
+#include <signal.h>
+#include "engine.h"
+
+
+class JStack : public Engine {
+  private:
+    static void signalHandler(int signo, siginfo_t* siginfo, void* ucontext);
+
+  public:
+    const char* name() {
+        return EVENT_JSTACK;
+    }
+
+    const char* units() {
+        return "samples";
+    }
+
+    Error start(Arguments& args);
+    void stop();
+};
+
+#endif // _JSTACK_H

src/linearAllocator.cpp

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "linearAllocator.h"
+#include "os.h"
+
+
+LinearAllocator::LinearAllocator(size_t chunk_size) {
+    _chunk_size = chunk_size;
+    _reserve = _tail = allocateChunk(NULL);
+}
+
+LinearAllocator::~LinearAllocator() {
+    clear();
+    freeChunk(_tail);
+}
+
+void LinearAllocator::clear() {
+    if (_reserve->prev == _tail) {
+        freeChunk(_reserve);
+    }
+    while (_tail->prev != NULL) {
+        Chunk* current = _tail;
+        _tail = _tail->prev;
+        freeChunk(current);
+    }
+    _reserve = _tail;
+    _tail->offs = sizeof(Chunk);
+}
+
+void* LinearAllocator::alloc(size_t size) {
+    Chunk* chunk = _tail;
+
+    do {
+        // Fast path: bump a pointer with CAS
+        for (size_t offs = chunk->offs; offs + size <= _chunk_size; offs = chunk->offs) {
+            if (__sync_bool_compare_and_swap(&chunk->offs, offs, offs + size)) {
+                if (_chunk_size / 2 - offs < size) {
+                    // Stepped over a middle of the chunk - it's time to prepare a new one
+                    reserveChunk(chunk);
+                }
+                return (char*)chunk + offs;
+            }
+        }
+    } while ((chunk = getNextChunk(chunk)) != NULL);
+
+    return NULL;
+}
+
+Chunk* LinearAllocator::allocateChunk(Chunk* current) {
+    Chunk* chunk = (Chunk*)OS::safeAlloc(_chunk_size);
+    if (chunk != NULL) {
+        chunk->prev = current;
+        chunk->offs = sizeof(Chunk);
+    }
+    return chunk;
+}
+
+void LinearAllocator::freeChunk(Chunk* current) {
+    OS::safeFree(current, _chunk_size);
+}
+
+void LinearAllocator::reserveChunk(Chunk* current) {
+    Chunk* reserve = allocateChunk(current);
+    if (reserve != NULL && !__sync_bool_compare_and_swap(&_reserve, current, reserve)) {
+        // Unlikely case that we are too late
+        freeChunk(reserve);
+    }
+}
+
+Chunk* LinearAllocator::getNextChunk(Chunk* current) {
+    Chunk* reserve = _reserve;
+
+    if (reserve == current) {
+        // Unlikely case: no reserve yet.
+        // It's probably being allocated right now, so let's compete
+        reserve = allocateChunk(current);
+        if (reserve == NULL) {
+            // Not enough memory
+            return NULL;
+        }
+
+        Chunk* prev_reserve = __sync_val_compare_and_swap(&_reserve, current, reserve);
+        if (prev_reserve != current) {
+            freeChunk(reserve);
+            reserve = prev_reserve;
+        }
+    }
+
+    // Expected case: a new chunk is already reserved
+    Chunk* tail = __sync_val_compare_and_swap(&_tail, current, reserve);
+    return tail == current ? reserve : tail;
+}

src/linearAllocator.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _LINEARALLOCATOR_H
+#define _LINEARALLOCATOR_H
+
+#include <stddef.h>
+
+
+struct Chunk {
+    Chunk* prev;
+    volatile size_t offs;
+    // To avoid false sharing
+    char _padding[56];
+};
+
+class LinearAllocator {
+  private:
+    size_t _chunk_size;
+    Chunk* _tail;
+    Chunk* _reserve;
+
+    Chunk* allocateChunk(Chunk* current);
+    void freeChunk(Chunk* current);
+    void reserveChunk(Chunk* current);
+    Chunk* getNextChunk(Chunk* current);
+
+  public:
+    LinearAllocator(size_t chunk_size);
+    ~LinearAllocator();
+
+    void clear();
+
+    void* alloc(size_t size);
+};
+
+#endif // _LINEARALLOCATOR_H

src/lockTracer.cpp

@@ -16,6 +16,7 @@
 
 #include <string.h>
 #include "lockTracer.h"
+#include "os.h"
 #include "profiler.h"
 #include "vmStructs.h"
 
@@ -23,20 +24,13 @@
 jlong LockTracer::_start_time = 0;
 jclass LockTracer::_LockSupport = NULL;
 jmethodID LockTracer::_getBlocker = NULL;
-UnsafeParkFunc LockTracer::_original_Unsafe_Park = NULL;
-bool LockTracer::_supports_lock_names = false;
 
 Error LockTracer::start(Arguments& args) {
-    // PermGen in JDK 7 makes difficult to get symbol name from jclass.
-    // Also some JVMs do not support VMStructs at all.
-    // Let's just record stack traces without lock names in these cases.
-    _supports_lock_names = VMStructs::available() && !VMStructs::hasPermGen();
-
     // Enable Java Monitor events
     jvmtiEnv* jvmti = VM::jvmti();
     jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_MONITOR_CONTENDED_ENTER, NULL);
     jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_MONITOR_CONTENDED_ENTERED, NULL);
-    jvmti->GetTime(&_start_time);
+    _start_time = OS::nanotime();
 
     if (_getBlocker == NULL) {
         JNIEnv* env = VM::jni();
@@ -44,13 +38,8 @@ Error LockTracer::start(Arguments& args) {
         _getBlocker = env->GetStaticMethodID(_LockSupport, "getBlocker", "(Ljava/lang/Thread;)Ljava/lang/Object;");
     }
 
-    if (_original_Unsafe_Park == NULL) {
-        NativeCodeCache* libjvm = Profiler::_instance.jvmLibrary();
-        _original_Unsafe_Park = (UnsafeParkFunc)libjvm->findSymbol("Unsafe_Park");
-    }
-
     // Intercent Unsafe.park() for tracing contended ReentrantLocks
-    if (_original_Unsafe_Park != NULL) {
+    if (VMStructs::_unsafe_park != NULL) {
         bindUnsafePark(UnsafeParkTrap);
     }
 
@@ -64,81 +53,94 @@ void LockTracer::stop() {
     jvmti->SetEventNotificationMode(JVMTI_DISABLE, JVMTI_EVENT_MONITOR_CONTENDED_ENTERED, NULL);
 
     // Reset Unsafe.park() trap
-    if (_original_Unsafe_Park != NULL) {
-        bindUnsafePark(_original_Unsafe_Park);
+    if (VMStructs::_unsafe_park != NULL) {
+        bindUnsafePark(VMStructs::_unsafe_park);
     }
 }
 
 void JNICALL LockTracer::MonitorContendedEnter(jvmtiEnv* jvmti, JNIEnv* env, jthread thread, jobject object) {
-    jlong enter_time;
-    jvmti->GetTime(&enter_time);
+    jlong enter_time = OS::nanotime();
     jvmti->SetTag(thread, enter_time);
 }
 
 void JNICALL LockTracer::MonitorContendedEntered(jvmtiEnv* jvmti, JNIEnv* env, jthread thread, jobject object) {
-    jlong enter_time, entered_time;
-    jvmti->GetTime(&entered_time);
+    jlong entered_time = OS::nanotime();
+    jlong enter_time;
     jvmti->GetTag(thread, &enter_time);
 
     // Time is meaningless if lock attempt has started before profiling
-    if (enter_time >= _start_time) {
-        recordContendedLock(env->GetObjectClass(object), entered_time - enter_time);
+    if (_enabled && enter_time >= _start_time) {
+        char* lock_name = getLockName(jvmti, env, object);
+        recordContendedLock(BCI_LOCK, enter_time, entered_time, lock_name, object, 0);
+        jvmti->Deallocate((unsigned char*)lock_name);
     }
 }
 
 void JNICALL LockTracer::UnsafeParkTrap(JNIEnv* env, jobject instance, jboolean isAbsolute, jlong time) {
     jvmtiEnv* jvmti = VM::jvmti();
-    jclass lock_class = getParkBlockerClass(jvmti, env);
+    jobject park_blocker = _enabled ? getParkBlocker(jvmti, env) : NULL;
     jlong park_start_time, park_end_time;
 
-    if (lock_class != NULL) {
-        jvmti->GetTime(&park_start_time);
+    if (park_blocker != NULL) {
+        park_start_time = OS::nanotime();
     }
-    
-    _original_Unsafe_Park(env, instance, isAbsolute, time);
 
-    if (lock_class != NULL) {
-        jvmti->GetTime(&park_end_time);
-        recordContendedLock(lock_class, park_end_time - park_start_time);
+    VMStructs::_unsafe_park(env, instance, isAbsolute, time);
+
+    if (park_blocker != NULL) {
+        park_end_time = OS::nanotime();
+
+        char* lock_name = getLockName(jvmti, env, park_blocker);
+        if (lock_name == NULL || isConcurrentLock(lock_name)) {
+            recordContendedLock(BCI_PARK, park_start_time, park_end_time, lock_name, park_blocker, time);
+        }
+        jvmti->Deallocate((unsigned char*)lock_name);
     }
 }
 
-jclass LockTracer::getParkBlockerClass(jvmtiEnv* jvmti, JNIEnv* env) {
+jobject LockTracer::getParkBlocker(jvmtiEnv* jvmti, JNIEnv* env) {
     jthread thread;
     if (jvmti->GetCurrentThread(&thread) != 0) {
         return NULL;
     }
 
     // Call LockSupport.getBlocker(Thread.currentThread())
-    jobject park_blocker = env->CallStaticObjectMethod(_LockSupport, _getBlocker, thread);
-    if (park_blocker == NULL) {
-        return NULL;
-    }
-
-    jclass lock_class = env->GetObjectClass(park_blocker);
-    char* class_name;
-    if (jvmti->GetClassSignature(lock_class, &class_name, NULL) != 0) {
-        return NULL;
-    }
-
-    // Do not count synchronizers other than ReentrantLock, ReentrantReadWriteLock and Semaphore
-    if (strncmp(class_name, "Ljava/util/concurrent/locks/ReentrantLock", 41) != 0 &&
-        strncmp(class_name, "Ljava/util/concurrent/locks/ReentrantReadWriteLock", 50) != 0 &&
-        strncmp(class_name, "Ljava/util/concurrent/Semaphore", 31) != 0) {
-        lock_class = NULL;
-    }
-
-    jvmti->Deallocate((unsigned char*)class_name);
-    return lock_class;
+    return env->CallStaticObjectMethod(_LockSupport, _getBlocker, thread);
 }
 
-void LockTracer::recordContendedLock(jclass lock_class, jlong time) {
-    if (_supports_lock_names) {
-        VMSymbol* lock_name = (*(java_lang_Class**)lock_class)->klass()->name();
-        Profiler::_instance.recordSample(NULL, time, BCI_SYMBOL, (jmethodID)lock_name);
-    } else {
-        Profiler::_instance.recordSample(NULL, time, BCI_SYMBOL, NULL);
+char* LockTracer::getLockName(jvmtiEnv* jvmti, JNIEnv* env, jobject lock) {
+    char* class_name;
+    if (jvmti->GetClassSignature(env->GetObjectClass(lock), &class_name, NULL) != 0) {
+        return NULL;
     }
+    return class_name;
+}
+
+bool LockTracer::isConcurrentLock(const char* lock_name) {
+    // Do not count synchronizers other than ReentrantLock, ReentrantReadWriteLock and Semaphore
+    return strncmp(lock_name, "Ljava/util/concurrent/locks/ReentrantLock", 41) == 0 ||
+           strncmp(lock_name, "Ljava/util/concurrent/locks/ReentrantReadWriteLock", 50) == 0 ||
+           strncmp(lock_name, "Ljava/util/concurrent/Semaphore", 31) == 0;
+}
+
+void LockTracer::recordContendedLock(int event_type, u64 start_time, u64 end_time,
+                                     const char* lock_name, jobject lock, jlong timeout) {
+    LockEvent event;
+    event._class_id = 0;
+    event._start_time = start_time;
+    event._end_time = end_time;
+    event._address = *(uintptr_t*)lock;
+    event._timeout = timeout;
+
+    if (lock_name != NULL) {
+        if (lock_name[0] == 'L') {
+            event._class_id = Profiler::_instance.classMap()->lookup(lock_name + 1, strlen(lock_name) - 2);
+        } else {
+            event._class_id = Profiler::_instance.classMap()->lookup(lock_name);
+        }
+    }
+
+    Profiler::_instance.recordSample(NULL, end_time - start_time, event_type, &event);
 }
 
 void LockTracer::bindUnsafePark(UnsafeParkFunc entry) {

src/lockTracer.h

@@ -18,6 +18,7 @@
 #define _LOCKTRACER_H
 
 #include <jvmti.h>
+#include "arch.h"
 #include "engine.h"
 
 
@@ -28,11 +29,12 @@ class LockTracer : public Engine {
     static jlong _start_time;
     static jclass _LockSupport;
     static jmethodID _getBlocker;
-    static UnsafeParkFunc _original_Unsafe_Park;
-    static bool _supports_lock_names;
 
-    static jclass getParkBlockerClass(jvmtiEnv* jvmti, JNIEnv* env);
-    static void recordContendedLock(jclass lock_class, jlong time);
+    static jobject getParkBlocker(jvmtiEnv* jvmti, JNIEnv* env);
+    static char* getLockName(jvmtiEnv* jvmti, JNIEnv* env, jobject lock);
+    static bool isConcurrentLock(const char* lock_name);
+    static void recordContendedLock(int event_type, u64 start_time, u64 end_time,
+                                    const char* lock_name, jobject lock, jlong timeout);
     static void bindUnsafePark(UnsafeParkFunc entry);
 
   public:
@@ -44,6 +46,10 @@ class LockTracer : public Engine {
         return "ns";
     }
 
+    CStack cstack() {
+        return CSTACK_NO;
+    }
+
     Error start(Arguments& args);
     void stop();
 

src/os.h

@@ -18,28 +18,65 @@
 #define _OS_H
 
 #include <signal.h>
+#include <stddef.h>
 #include "arch.h"
 
 
+enum ThreadState {
+    THREAD_INVALID,
+    THREAD_RUNNING,
+    THREAD_SLEEPING
+};
+
+
+class Timer {
+};
+
+
 class ThreadList {
   public:
     virtual ~ThreadList() {}
+    virtual void rewind() = 0;
     virtual int next() = 0;
+    virtual int size() = 0;
 };
 
 
 class OS {
+  private:
+    typedef void (*SigAction)(int, siginfo_t*, void*);
+    typedef void (*SigHandler)(int);
+    typedef void (*TimerCallback)(void*);
+
   public:
     static u64 nanotime();
     static u64 millis();
+    static u64 processStartTime();
+
     static u64 hton64(u64 x);
+    static u64 ntoh64(u64 x);
+
+    static int getMaxThreadId();
+    static int processId();
     static int threadId();
-    static bool isThreadRunning(int thread_id);
-    static bool isSignalSafeTLS();
-    static bool isJavaLibraryVisible();
-    static void installSignalHandler(int signo, void (*handler)(int, siginfo_t*, void*));
-    static void sendSignalToThread(int thread_id, int signo);
+    static bool threadName(int thread_id, char* name_buf, size_t name_len);
+    static ThreadState threadState(int thread_id);
     static ThreadList* listThreads();
+
+    static bool isJavaLibraryVisible();
+
+    static void installSignalHandler(int signo, SigAction action, SigHandler handler = NULL);
+    static bool sendSignalToThread(int thread_id, int signo);
+
+    static void* safeAlloc(size_t size);
+    static void safeFree(void* addr, size_t size);
+
+    static Timer* startTimer(u64 interval, TimerCallback callback, void* arg);
+    static void stopTimer(Timer* timer);
+
+    static bool getCpuDescription(char* buf, size_t size);
+    static u64 getProcessCpuTime(u64* utime, u64* stime);
+    static u64 getTotalCpuTime(u64* utime, u64* stime);
 };
 
 #endif // _OS_H

src/os_linux.cpp

@@ -23,22 +23,54 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/syscall.h>
 #include <sys/time.h>
+#include <sys/times.h>
 #include <sys/types.h>
 #include <time.h>
 #include <unistd.h>
 #include "os.h"
 
 
+#ifdef __LP64__
+#  define MMAP_SYSCALL __NR_mmap
+#else
+#  define MMAP_SYSCALL __NR_mmap2
+#endif
+
+
 class LinuxThreadList : public ThreadList {
   private:
     DIR* _dir;
+    int _thread_count;
+
+    int getThreadCount() {
+        char buf[512];
+        int fd = open("/proc/self/stat", O_RDONLY);
+        if (fd == -1) {
+            return 0;
+        }
+
+        int thread_count = 0;
+        if (read(fd, buf, sizeof(buf)) > 0) {
+            char* s = strchr(buf, ')');
+            if (s != NULL) {
+                // Read 18th integer field after the command name
+                for (int field = 0; *s != ' ' || ++field < 18; s++) ;
+                thread_count = atoi(s + 1);
+            }
+        }
+
+        close(fd);
+        return thread_count;
+    }
 
   public:
     LinuxThreadList() {
         _dir = opendir("/proc/self/task");
+        _thread_count = -1;
     }
 
     ~LinuxThreadList() {
@@ -47,6 +79,13 @@ class LinuxThreadList : public ThreadList {
         }
     }
 
+    void rewind() {
+        if (_dir != NULL) {
+            rewinddir(_dir);
+        }
+        _thread_count = -1;
+    }
+
     int next() {
         if (_dir != NULL) {
             struct dirent* entry;
@@ -58,6 +97,13 @@ class LinuxThreadList : public ThreadList {
         }
         return -1;
     }
+
+    int size() {
+        if (_thread_count < 0) {
+            _thread_count = getThreadCount();
+        }
+        return _thread_count;
+    }
 };
 
 
@@ -73,57 +119,201 @@ u64 OS::millis() {
     return (u64)tv.tv_sec * 1000 + tv.tv_usec / 1000;
 }
 
+u64 OS::processStartTime() {
+    static u64 start_time = 0;
+
+    if (start_time == 0) {
+        char buf[64];
+        sprintf(buf, "/proc/%d", processId());
+
+        struct stat st;
+        if (stat(buf, &st) == 0) {
+            start_time = (u64)st.st_mtim.tv_sec * 1000 + st.st_mtim.tv_nsec / 1000000;
+        }
+    }
+
+    return start_time;
+}
+
 u64 OS::hton64(u64 x) {
     return htonl(1) == 1 ? x : bswap_64(x);
 }
 
+u64 OS::ntoh64(u64 x) {
+    return ntohl(1) == 1 ? x : bswap_64(x);
+}
+
+int OS::getMaxThreadId() {
+    char buf[16] = "65536";
+    int fd = open("/proc/sys/kernel/pid_max", O_RDONLY);
+    if (fd != -1) {
+        ssize_t r = read(fd, buf, sizeof(buf) - 1);
+        (void) r;
+        close(fd);
+    }
+    return atoi(buf);
+}
+
+int OS::processId() {
+    static const int self_pid = getpid();
+
+    return self_pid;
+}
+
 int OS::threadId() {
     return syscall(__NR_gettid);
 }
 
-bool OS::isThreadRunning(int thread_id) {
-    char buf[512];
-    sprintf(buf, "/proc/self/task/%d/stat", thread_id);
+bool OS::threadName(int thread_id, char* name_buf, size_t name_len) {
+    char buf[64];
+    sprintf(buf, "/proc/self/task/%d/comm", thread_id);
     int fd = open(buf, O_RDONLY);
     if (fd == -1) {
         return false;
     }
 
-    bool running = false;
-    if (read(fd, buf, sizeof(buf)) > 0) {
-        char* s = strchr(buf, ')');
-        running = s != NULL && (s[2] == 'R' || s[2] == 'D');
-    }
-
+    ssize_t r = read(fd, name_buf, name_len);
     close(fd);
-    return running;
-}
 
-bool OS::isSignalSafeTLS() {
-    return true;
-}
-
-bool OS::isJavaLibraryVisible() {
+    if (r > 0) {
+        name_buf[r - 1] = 0;
+        return true;
+    }
     return false;
 }
 
-void OS::installSignalHandler(int signo, void (*handler)(int, siginfo_t*, void*)) {
-    struct sigaction sa;
-    sigemptyset(&sa.sa_mask);
-    sa.sa_sigaction = handler;
-    sa.sa_flags = SA_RESTART | SA_SIGINFO;
+ThreadState OS::threadState(int thread_id) {
+    char buf[512];
+    sprintf(buf, "/proc/self/task/%d/stat", thread_id);
+    int fd = open(buf, O_RDONLY);
+    if (fd == -1) {
+        return THREAD_INVALID;
+    }
 
-    sigaction(signo, &sa, NULL);
-}
+    ThreadState state = THREAD_INVALID;
+    if (read(fd, buf, sizeof(buf)) > 0) {
+        char* s = strchr(buf, ')');
+        state = s != NULL && (s[2] == 'R' || s[2] == 'D') ? THREAD_RUNNING : THREAD_SLEEPING;
+    }
 
-void OS::sendSignalToThread(int thread_id, int signo) {
-    static const int self_pid = getpid();
-
-    syscall(__NR_tgkill, self_pid, thread_id, signo);
+    close(fd);
+    return state;
 }
 
 ThreadList* OS::listThreads() {
     return new LinuxThreadList();
 }
 
+bool OS::isJavaLibraryVisible() {
+    return false;
+}
+
+void OS::installSignalHandler(int signo, SigAction action, SigHandler handler) {
+    struct sigaction sa;
+    sigemptyset(&sa.sa_mask);
+
+    if (handler != NULL) {
+        sa.sa_handler = handler;
+        sa.sa_flags = 0;
+    } else {
+        sa.sa_sigaction = action;
+        sa.sa_flags = SA_SIGINFO | SA_RESTART;
+    }
+
+    sigaction(signo, &sa, NULL);
+}
+
+bool OS::sendSignalToThread(int thread_id, int signo) {
+    return syscall(__NR_tgkill, processId(), thread_id, signo) == 0;
+}
+
+void* OS::safeAlloc(size_t size) {
+    // Naked syscall can be used inside a signal handler.
+    // Also, we don't want to catch our own calls when profiling mmap.
+    intptr_t result = syscall(MMAP_SYSCALL, NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    if (result < 0 && result > -4096) {
+        return NULL;
+    }
+    return (void*)result;
+}
+
+void OS::safeFree(void* addr, size_t size) {
+    syscall(__NR_munmap, addr, size);
+}
+
+Timer* OS::startTimer(u64 interval, TimerCallback callback, void* arg) {
+    struct sigevent sev;
+    sev.sigev_notify = SIGEV_THREAD;
+    sev.sigev_value.sival_ptr = arg;
+    sev.sigev_notify_function = (void (*)(union sigval)) callback;
+    sev.sigev_notify_attributes = NULL;
+
+    timer_t timer;
+    if (timer_create(CLOCK_MONOTONIC, &sev, &timer) != 0) {
+        return NULL;
+    }
+
+    struct itimerspec spec;
+    spec.it_interval.tv_sec = spec.it_value.tv_sec = interval / 1000000000;
+    spec.it_interval.tv_nsec = spec.it_value.tv_nsec = interval % 1000000000;
+    timer_settime(timer, 0, &spec, NULL);
+
+    return (Timer*)timer;
+}
+
+void OS::stopTimer(Timer* timer) {
+    timer_delete((timer_t)timer);
+}
+
+bool OS::getCpuDescription(char* buf, size_t size) {
+    int fd = open("/proc/cpuinfo", O_RDONLY);
+    if (fd == -1) {
+        return false;
+    }
+
+    ssize_t r = read(fd, buf, size);
+    close(fd);
+    if (r <= 0) {
+        return false;
+    }
+    buf[r < size ? r : size - 1] = 0;
+
+    char* c;
+    do {
+        c = strchr(buf, '\n');
+    } while (c != NULL && *(buf = c + 1) != '\n');
+
+    *buf = 0;
+    return true;
+}
+
+u64 OS::getProcessCpuTime(u64* utime, u64* stime) {
+    struct tms buf;
+    clock_t real = times(&buf);
+    *utime = buf.tms_utime;
+    *stime = buf.tms_stime;
+    return real;
+}
+
+u64 OS::getTotalCpuTime(u64* utime, u64* stime) {
+    int fd = open("/proc/stat", O_RDONLY);
+    if (fd == -1) {
+        return (u64)-1;
+    }
+
+    u64 real = (u64)-1;
+    char buf[512];
+    if (read(fd, buf, sizeof(buf)) >= 12) {
+        u64 user, nice, system, idle;
+        if (sscanf(buf + 4, "%llu %llu %llu  %llu", &user, &nice, &system, &idle) == 4) {
+            *utime = user + nice;
+            *stime = system;
+            real = user + nice + system + idle;
+        }
+    }
+
+    close(fd);
+    return real;
+}
+
 #endif // __linux__

src/os_macos.cpp

@@ -16,38 +16,68 @@
 
 #ifdef __APPLE__
 
+#include <dispatch/dispatch.h>
 #include <libkern/OSByteOrder.h>
+#include <libproc.h>
 #include <mach/mach.h>
+#include <mach/mach_host.h>
 #include <mach/mach_time.h>
+#include <mach/processor_info.h>
+#include <pthread.h>
+#include <sys/mman.h>
+#include <sys/sysctl.h>
 #include <sys/time.h>
+#include <sys/times.h>
 #include "os.h"
 
 
 class MacThreadList : public ThreadList {
   private:
+    task_t _task;
     thread_array_t _thread_array;
     unsigned int _thread_count;
     unsigned int _thread_index;
 
+    void ensureThreadArray() {
+        if (_thread_array == NULL) {
+            _thread_count = 0;
+            _thread_index = 0;
+            task_threads(_task, &_thread_array, &_thread_count);
+        }
+    }
+
   public:
-    MacThreadList() : _thread_array(NULL), _thread_count(0), _thread_index(0) {
-        task_threads(mach_task_self(), &_thread_array, &_thread_count);
+    MacThreadList() {
+        _task = mach_task_self();
+        _thread_array = NULL;
     }
 
     ~MacThreadList() {
-        task_t task = mach_task_self();
-        for (int i = 0; i < _thread_count; i++) {
-            mach_port_deallocate(task, _thread_array[i]);
+        rewind();
+    }
+
+    void rewind() {
+        if (_thread_array != NULL) {
+            for (int i = 0; i < _thread_count; i++) {
+                mach_port_deallocate(_task, _thread_array[i]);
+            }
+            vm_deallocate(_task, (vm_address_t)_thread_array, _thread_count * sizeof(thread_t));
+            _thread_array = NULL;
         }
-        vm_deallocate(task, (vm_address_t)_thread_array, sizeof(thread_t) * _thread_count);
     }
 
     int next() {
+        ensureThreadArray();
         if (_thread_index < _thread_count) {
             return (int)_thread_array[_thread_index++];
         }
         return -1;
     }
+
+    int size() {
+        ensureThreadArray();
+        return _thread_count;
+    }
 };
 
 
@@ -66,10 +96,37 @@ u64 OS::millis() {
     return (u64)tv.tv_sec * 1000 + tv.tv_usec / 1000;
 }
 
+u64 OS::processStartTime() {
+    static u64 start_time = 0;
+
+    if (start_time == 0) {
+        struct proc_bsdinfo info;
+        if (proc_pidinfo(processId(), PROC_PIDTBSDINFO, 0, &info, sizeof(info)) > 0) {
+            start_time = (u64)info.pbi_start_tvsec * 1000 + info.pbi_start_tvusec / 1000;
+        }
+    }
+
+    return start_time;
+}
+
 u64 OS::hton64(u64 x) {
     return OSSwapHostToBigInt64(x);
 }
 
+u64 OS::ntoh64(u64 x) {
+    return OSSwapBigToHostInt64(x);
+}
+
+int OS::getMaxThreadId() {
+    return 0x7fffffff;
+}
+
+int OS::processId() {
+    static const int self_pid = getpid();
+
+    return self_pid;
+}
+
 int OS::threadId() {
     // Used to be pthread_mach_thread_np(pthread_self()),
     // but pthread_mach_thread_np is not async signal safe
@@ -78,38 +135,124 @@ int OS::threadId() {
     return (int)port;
 }
 
-bool OS::isThreadRunning(int thread_id) {
+bool OS::threadName(int thread_id, char* name_buf, size_t name_len) {
+    pthread_t thread = pthread_from_mach_thread_np(thread_id);
+    return thread && pthread_getname_np(thread, name_buf, name_len) == 0 && name_buf[0] != 0;
+}
+
+ThreadState OS::threadState(int thread_id) {
     struct thread_basic_info info;
     mach_msg_type_number_t size = sizeof(info);
     if (thread_info((thread_act_t)thread_id, THREAD_BASIC_INFO, (thread_info_t)&info, &size) != 0) {
-        return false;
+        return THREAD_INVALID;
     }
-    return info.run_state == TH_STATE_RUNNING;
-}
-
-bool OS::isSignalSafeTLS() {
-    return false;
-}
-
-bool OS::isJavaLibraryVisible() {
-    return true;
-}
-
-void OS::installSignalHandler(int signo, void (*handler)(int, siginfo_t*, void*)) {
-    struct sigaction sa;
-    sigemptyset(&sa.sa_mask);
-    sa.sa_sigaction = handler;
-    sa.sa_flags = SA_RESTART | SA_SIGINFO;
-
-    sigaction(signo, &sa, NULL);
-}
-
-void OS::sendSignalToThread(int thread_id, int signo) {
-   asm volatile("syscall" : : "a"(0x2000148), "D"(thread_id), "S"(signo));
+    return info.run_state == TH_STATE_RUNNING ? THREAD_RUNNING : THREAD_SLEEPING;
 }
 
 ThreadList* OS::listThreads() {
     return new MacThreadList();
 }
 
+bool OS::isJavaLibraryVisible() {
+    return true;
+}
+
+void OS::installSignalHandler(int signo, SigAction action, SigHandler handler) {
+    struct sigaction sa;
+    sigemptyset(&sa.sa_mask);
+
+    if (handler != NULL) {
+        sa.sa_handler = handler;
+        sa.sa_flags = 0;
+    } else {
+        sa.sa_sigaction = action;
+        sa.sa_flags = SA_SIGINFO | SA_RESTART;
+    }
+
+    sigaction(signo, &sa, NULL);
+}
+
+bool OS::sendSignalToThread(int thread_id, int signo) {
+   int result;
+   asm volatile("syscall"
+                : "=a" (result)
+                : "a" (0x2000148), "D" (thread_id), "S" (signo)
+                : "rcx", "r11", "memory");
+   return result == 0;
+}
+
+void* OS::safeAlloc(size_t size) {
+    // mmap() is not guaranteed to be async signal safe, but in practice, it is.
+    // There is no a reasonable alternative anyway.
+    void* result = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    if (result == MAP_FAILED) {
+        return NULL;
+    }
+    return result;
+}
+
+void OS::safeFree(void* addr, size_t size) {
+    munmap(addr, size);
+}
+
+Timer* OS::startTimer(u64 interval, TimerCallback callback, void* arg) {
+    dispatch_queue_t queue = dispatch_get_global_queue(QOS_CLASS_UTILITY, 0);
+    dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
+    if (source != NULL) {
+        dispatch_source_set_timer(source, dispatch_time(DISPATCH_TIME_NOW, interval), interval, 0);
+        dispatch_source_set_event_handler_f(source, callback);
+        dispatch_set_context(source, arg);
+        dispatch_resume(source);
+    }
+    return (Timer*)source;
+}
+
+void OS::stopTimer(Timer* timer) {
+    dispatch_source_t source = (dispatch_source_t)timer;
+    if (source != NULL) {
+        dispatch_source_cancel(source);
+        dispatch_release(source);
+    }
+}
+
+bool OS::getCpuDescription(char* buf, size_t size) {
+    return sysctlbyname("machdep.cpu.brand_string", buf, &size, NULL, 0) == 0;
+}
+
+u64 OS::getProcessCpuTime(u64* utime, u64* stime) {
+    struct tms buf;
+    clock_t real = times(&buf);
+    *utime = buf.tms_utime;
+    *stime = buf.tms_stime;
+    return real;
+}
+
+u64 OS::getTotalCpuTime(u64* utime, u64* stime) {
+    natural_t cpu_count;
+    processor_info_array_t cpu_info_array;
+    mach_msg_type_number_t cpu_info_count;
+
+    host_name_port_t host = mach_host_self();
+    kern_return_t ret = host_processor_info(host, PROCESSOR_CPU_LOAD_INFO, &cpu_count, &cpu_info_array, &cpu_info_count);
+    mach_port_deallocate(mach_task_self(), host);
+    if (ret != 0) {
+        return (u64)-1;
+    }
+
+    processor_cpu_load_info_data_t* cpu_load = (processor_cpu_load_info_data_t*)cpu_info_array;
+    u64 user = 0;
+    u64 system = 0;
+    u64 idle = 0;
+    for (natural_t i = 0; i < cpu_count; i++) {
+        user += cpu_load[i].cpu_ticks[CPU_STATE_USER] + cpu_load[i].cpu_ticks[CPU_STATE_NICE];
+        system += cpu_load[i].cpu_ticks[CPU_STATE_SYSTEM];
+        idle += cpu_load[i].cpu_ticks[CPU_STATE_IDLE];
+    }
+    vm_deallocate(mach_task_self(), (vm_address_t)cpu_info_array, cpu_info_count * sizeof(int));
+
+    *utime = user;
+    *stime = system;
+    return user + system + idle;
+}
+
 #endif // __APPLE__

src/perfEvents.h

@@ -31,10 +31,9 @@ class PerfEvents : public Engine {
     static PerfEventType* _event_type;
     static long _interval;
     static Ring _ring;
+    static CStack _cstack;
     static bool _print_extended_warning;
 
-    static bool createForThread(int tid);
-    static void destroyForThread(int tid);
     static void signalHandler(int signo, siginfo_t* siginfo, void* ucontext);
 
   public:
@@ -44,17 +43,18 @@ class PerfEvents : public Engine {
 
     const char* units();
 
+    Error check(Arguments& args);
     Error start(Arguments& args);
     void stop();
 
-    void onThreadStart();
-    void onThreadEnd();
-
     int getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                       const void* jit_min_address, const void* jit_max_address);
+                       CodeCache* java_methods, CodeCache* runtime_stubs);
 
     static bool supported();
     static const char* getEventName(int event_id);
+
+    static bool createForThread(int tid);
+    static void destroyForThread(int tid);
 };
 
 #endif // _PERFEVENTS_H

src/perfEvents_linux.cpp

@@ -27,6 +27,7 @@
 #include <errno.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
+#include <sys/stat.h>
 #include <sys/syscall.h>
 #include <linux/perf_event.h>
 #include "arch.h"
@@ -35,6 +36,7 @@
 #include "profiler.h"
 #include "spinLock.h"
 #include "stackFrame.h"
+#include "symbols.h"
 
 
 // Ancient fcntl.h does not define F_SETOWN_EX constants and structures
@@ -59,17 +61,6 @@ enum {
 
 static const unsigned long PERF_PAGE_SIZE = sysconf(_SC_PAGESIZE);
 
-static int getMaxPID() {
-    char buf[16] = "65536";
-    int fd = open("/proc/sys/kernel/pid_max", O_RDONLY);
-    if (fd != -1) {
-        ssize_t r = read(fd, buf, sizeof(buf) - 1);
-        (void) r;
-        close(fd);
-    }
-    return atoi(buf);
-}
-
 // Get perf_event_attr.config numeric value of the given tracepoint name
 // by reading /sys/kernel/debug/tracing/events/<name>/id file
 static int findTracepointId(const char* name) {
@@ -137,7 +128,7 @@ struct PerfEventType {
 
         // Parse access type [:rwx]
         char* c = strrchr(buf, ':');
-        if (c != NULL) {
+        if (c != NULL && c != name && c[-1] != ':') {
             *c++ = 0;
             if (strcmp(c, "r") == 0) {
                 bp_type = HW_BREAKPOINT_R;
@@ -173,13 +164,14 @@ struct PerfEventType {
         } else {
             addr = (__u64)(uintptr_t)dlsym(RTLD_DEFAULT, buf);
             if (addr == 0) {
-                addr = (__u64)(uintptr_t)Profiler::_instance.findSymbol(buf);
-            }
-            if (addr == 0) {
-                return NULL;
+                addr = (__u64)(uintptr_t)Profiler::_instance.resolveSymbol(buf);
             }
         }
 
+        if (addr == 0) {
+            return NULL;
+        }
+
         PerfEventType* breakpoint = findByType(PERF_TYPE_BREAKPOINT);
         breakpoint->config = addr + offset;
         breakpoint->bp_type = bp_type;
@@ -214,7 +206,8 @@ struct PerfEventType {
         }
 
         // Kernel tracepoints defined in debugfs
-        if (strchr(name, ':') != NULL) {
+        const char* c = strchr(name, ':');
+        if (c != NULL && c[1] != ':') {
             int tracepoint_id = findTracepointId(name);
             if (tracepoint_id > 0) {
                 return getTracepoint(tracepoint_id);
@@ -285,6 +278,11 @@ class RingBuffer {
         _offset = (_offset + sizeof(u64)) & (PERF_PAGE_SIZE - 1);
         return *(u64*)(_start + _offset);
     }
+
+    u64 peek(unsigned long words) {
+        unsigned long peek_offset = (_offset + words * sizeof(u64)) & (PERF_PAGE_SIZE - 1);
+        return *(u64*)(_start + peek_offset);
+    }
 };
 
 
@@ -302,6 +300,7 @@ PerfEvent* PerfEvents::_events = NULL;
 PerfEventType* PerfEvents::_event_type = NULL;
 long PerfEvents::_interval;
 Ring PerfEvents::_ring;
+CStack PerfEvents::_cstack;
 bool PerfEvents::_print_extended_warning;
 
 bool PerfEvents::createForThread(int tid) {
@@ -343,13 +342,24 @@ bool PerfEvents::createForThread(int tid) {
         attr.exclude_user = 1;
     }
 
+#ifdef PERF_ATTR_SIZE_VER5
+    if (_cstack == CSTACK_LBR) {
+        attr.sample_type |= PERF_SAMPLE_BRANCH_STACK | PERF_SAMPLE_REGS_USER;
+        attr.branch_sample_type = PERF_SAMPLE_BRANCH_USER | PERF_SAMPLE_BRANCH_CALL_STACK;
+        attr.sample_regs_user = 1ULL << PERF_REG_PC;
+        attr.exclude_callchain_user = 1;
+    }
+#else
+#warning "Compiling without LBR support. Kernel headers 4.1+ required"
+#endif
+
     int fd = syscall(__NR_perf_event_open, &attr, tid, -1, -1, 0);
     if (fd == -1) {
         int err = errno;
         perror("perf_event_open failed");
         if (err == EACCES && _print_extended_warning) {
-            fprintf(stderr, "Due to permission restrictions, you cannot collect kernel events.\n");
-            fprintf(stderr, "Try with --all-user option, or 'echo 1 > /proc/sys/kernel/perf_event_paranoid'\n");
+            fprintf(stderr, "Due to permission restrictions, you cannot collect kernel events.\n"
+                            "Try with --all-user option, or 'echo 1 > /proc/sys/kernel/perf_event_paranoid'\n");
             _print_extended_warning = false;
         }
         return false;
@@ -409,19 +419,23 @@ void PerfEvents::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {
         return;
     }
 
-    u64 counter;
-    switch (_event_type->counter_arg) {
-        case 1: counter = StackFrame(ucontext).arg0(); break;
-        case 2: counter = StackFrame(ucontext).arg1(); break;
-        case 3: counter = StackFrame(ucontext).arg2(); break;
-        case 4: counter = StackFrame(ucontext).arg3(); break;
-        default:
-            if (read(siginfo->si_fd, &counter, sizeof(counter)) != sizeof(counter)) {
-                counter = 1;
-            }
+    if (_enabled) {
+        u64 counter;
+        switch (_event_type->counter_arg) {
+            case 1: counter = StackFrame(ucontext).arg0(); break;
+            case 2: counter = StackFrame(ucontext).arg1(); break;
+            case 3: counter = StackFrame(ucontext).arg2(); break;
+            case 4: counter = StackFrame(ucontext).arg3(); break;
+            default:
+                if (read(siginfo->si_fd, &counter, sizeof(counter)) != sizeof(counter)) {
+                    counter = 1;
+                }
+        }
+
+        ExecutionEvent event;
+        Profiler::_instance.recordSample(ucontext, counter, 0, &event);
     }
 
-    Profiler::_instance.recordSample(ucontext, counter, 0, NULL);
     ioctl(siginfo->si_fd, PERF_EVENT_IOC_RESET, 0);
     ioctl(siginfo->si_fd, PERF_EVENT_IOC_REFRESH, 1);
 }
@@ -437,8 +451,57 @@ const char* PerfEvents::units() {
     return dash != NULL ? dash + 1 : _event_type->name;
 }
 
+Error PerfEvents::check(Arguments& args) {
+    PerfEventType* event_type = PerfEventType::forName(args._event_desc);
+    if (event_type == NULL) {
+        return Error("Unsupported event type");
+    }
+
+    struct perf_event_attr attr = {0};
+    attr.size = sizeof(attr);
+    attr.type = event_type->type;
+
+    if (attr.type == PERF_TYPE_BREAKPOINT) {
+        attr.bp_addr = event_type->config;
+        attr.bp_type = event_type->bp_type;
+        attr.bp_len = event_type->bp_len;
+    } else {
+        attr.config = event_type->config;
+    }
+
+    attr.sample_period = event_type->default_interval;
+    attr.sample_type = PERF_SAMPLE_CALLCHAIN;
+    attr.disabled = 1;
+
+    if (args._ring == RING_USER) {
+        attr.exclude_kernel = 1;
+    } else if (args._ring == RING_KERNEL) {
+        attr.exclude_user = 1;
+    } else if (!Symbols::haveKernelSymbols()) {
+        Profiler::_instance.updateSymbols(true);
+        attr.exclude_kernel = Symbols::haveKernelSymbols() ? 0 : 1;
+    }
+
+#ifdef PERF_ATTR_SIZE_VER5
+    if (args._cstack == CSTACK_LBR) {
+        attr.sample_type |= PERF_SAMPLE_BRANCH_STACK | PERF_SAMPLE_REGS_USER;
+        attr.branch_sample_type = PERF_SAMPLE_BRANCH_USER | PERF_SAMPLE_BRANCH_CALL_STACK;
+        attr.sample_regs_user = 1ULL << PERF_REG_PC;
+        attr.exclude_callchain_user = 1;
+    }
+#endif
+
+    int fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
+    if (fd == -1) {
+        return Error(strerror(errno));
+    }
+
+    close(fd);
+    return Error::OK;
+}
+
 Error PerfEvents::start(Arguments& args) {
-    _event_type = PerfEventType::forName(args._event);
+    _event_type = PerfEventType::forName(args._event_desc);
     if (_event_type == NULL) {
         return Error("Unsupported event type");
     }
@@ -449,15 +512,22 @@ Error PerfEvents::start(Arguments& args) {
     _interval = args._interval ? args._interval : _event_type->default_interval;
 
     _ring = args._ring;
+    if (_ring != RING_USER && !Symbols::haveKernelSymbols()) {
+        fprintf(stderr, "WARNING: Kernel symbols are unavailable due to restrictions. Try\n"
+                        "  echo 0 > /proc/sys/kernel/kptr_restrict\n"
+                        "  echo 1 > /proc/sys/kernel/perf_event_paranoid\n");
+        _ring = RING_USER;
+    }
+    _cstack = args._cstack;
     _print_extended_warning = _ring != RING_USER;
 
-    int max_events = getMaxPID();
+    int max_events = OS::getMaxThreadId();
     if (max_events != _max_events) {
         free(_events);
         _events = (PerfEvent*)calloc(max_events, sizeof(PerfEvent));
         _max_events = max_events;
     }
-    
+
     OS::installSignalHandler(SIGPROF, signalHandler);
 
     // Enable thread events before traversing currently running threads
@@ -484,16 +554,8 @@ void PerfEvents::stop() {
     }
 }
 
-void PerfEvents::onThreadStart() {
-    createForThread(OS::threadId());
-}
-
-void PerfEvents::onThreadEnd() {
-    destroyForThread(OS::threadId());
-}
-
 int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                               const void* jit_min_address, const void* jit_max_address) {
+                               CodeCache* java_methods, CodeCache* runtime_stubs) {
     PerfEvent* event = &_events[tid];
     if (!event->tryLock()) {
         return 0;  // the event is being destroyed
@@ -513,22 +575,51 @@ int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain,
             struct perf_event_header* hdr = ring.seek(tail);
             if (hdr->type == PERF_RECORD_SAMPLE) {
                 u64 nr = ring.next();
-                while (nr-- > 0 && depth < max_depth) {
+                while (nr-- > 0) {
                     u64 ip = ring.next();
                     if (ip < PERF_CONTEXT_MAX) {
                         const void* iptr = (const void*)ip;
-                        callchain[depth++] = iptr;
-                        if (iptr >= jit_min_address && iptr < jit_max_address) {
+                        if (java_methods->contains(iptr) || runtime_stubs->contains(iptr) || depth >= max_depth) {
                             // Stop at the first Java frame
-                            break;
+                            goto stack_complete;
                         }
+                        callchain[depth++] = iptr;
                     }
                 }
+
+                if (_cstack == CSTACK_LBR) {
+                    u64 bnr = ring.next();
+
+                    // Last userspace PC is stored right after branch stack
+                    const void* pc = (const void*)ring.peek(bnr * 3 + 2);
+                    if (java_methods->contains(pc) || runtime_stubs->contains(pc) || depth >= max_depth) {
+                        goto stack_complete;
+                    }
+                    callchain[depth++] = pc;
+
+                    while (bnr-- > 0) {
+                        const void* from = (const void*)ring.next();
+                        const void* to = (const void*)ring.next();
+                        ring.next();
+
+                        if (java_methods->contains(to) || runtime_stubs->contains(to) || depth >= max_depth) {
+                            goto stack_complete;
+                        }
+                        callchain[depth++] = to;
+
+                        if (java_methods->contains(from) || runtime_stubs->contains(from) || depth >= max_depth) {
+                            goto stack_complete;
+                        }
+                        callchain[depth++] = from;
+                    }
+                }
+
                 break;
             }
             tail += hdr->size;
         }
 
+stack_complete:
         page->data_tail = head;
     }
 
@@ -537,7 +628,10 @@ int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain,
 }
 
 bool PerfEvents::supported() {
-    return true;
+    // The official way of knowing if perf_event_open() support is enabled
+    // is checking for the existence of the file /proc/sys/kernel/perf_event_paranoid
+    struct stat statbuf;
+    return stat("/proc/sys/kernel/perf_event_paranoid", &statbuf) == 0;
 }
 
 const char* PerfEvents::getEventName(int event_id) {

src/perfEvents_macos.cpp

@@ -27,14 +27,17 @@ Ring PerfEvents::_ring;
 bool PerfEvents::_print_extended_warning;
 
 
-bool PerfEvents::createForThread(int tid) { return false; }
-void PerfEvents::destroyForThread(int tid) {}
-void PerfEvents::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {}
+void PerfEvents::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {
+}
 
 const char* PerfEvents::units() {
     return "ns";
 }
 
+Error PerfEvents::check(Arguments& args) {
+    return Error("PerfEvents are unsupported on macOS");
+}
+
 Error PerfEvents::start(Arguments& args) {
     return Error("PerfEvents are unsupported on macOS");
 }
@@ -42,14 +45,8 @@ Error PerfEvents::start(Arguments& args) {
 void PerfEvents::stop() {
 }
 
-void PerfEvents::onThreadStart() {
-}
-
-void PerfEvents::onThreadEnd() {
-}
-
 int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                               const void* jit_min_address, const void* jit_max_address) {
+                               CodeCache* java_methods, CodeCache* runtime_stubs) {
     return 0;
 }
 
@@ -61,4 +58,11 @@ const char* PerfEvents::getEventName(int event_id) {
     return NULL;
 }
 
+bool PerfEvents::createForThread(int tid) {
+    return false;
+}
+
+void PerfEvents::destroyForThread(int tid) {
+}
+
 #endif // __APPLE__

src/profiler.h

@@ -22,28 +22,35 @@
 #include <time.h>
 #include "arch.h"
 #include "arguments.h"
+#include "callTraceStorage.h"
+#include "codeCache.h"
+#include "dictionary.h"
 #include "engine.h"
+#include "event.h"
 #include "flightRecorder.h"
 #include "mutex.h"
 #include "spinLock.h"
-#include "codeCache.h"
+#include "threadFilter.h"
+#include "trap.h"
 #include "vmEntry.h"
 
 
 const char FULL_VERSION_STRING[] =
     "Async-profiler " PROFILER_VERSION " built on " __DATE__ "\n"
-    "Copyright 2019 Andrei Pangin\n";
+    "Copyright 2016-2021 Andrei Pangin\n";
 
-const int MAX_CALLTRACES    = 65536;
 const int MAX_NATIVE_FRAMES = 128;
 const int RESERVED_FRAMES   = 4;
 const int MAX_NATIVE_LIBS   = 2048;
 const int CONCURRENCY_LEVEL = 16;
 
 
-static inline int cmp64(u64 a, u64 b) {
-    return a > b ? 1 : a == b ? 0 : -1;
-}
+enum AddressType {
+    ADDR_UNKNOWN,
+    ADDR_JIT,
+    ADDR_STUB,
+    ADDR_NATIVE
+};
 
 
 union CallTraceBuffer {
@@ -52,38 +59,7 @@ union CallTraceBuffer {
 };
 
 
-class CallTraceSample {
-  private:
-    u64 _samples;
-    u64 _counter;
-    int _start_frame; // Offset in frame buffer
-    int _num_frames;
-
-  public:
-    static int comparator(const void* s1, const void* s2) {
-        return cmp64((*(CallTraceSample**)s2)->_counter, (*(CallTraceSample**)s1)->_counter);
-    }
-
-    friend class Profiler;
-    friend class Recording;
-};
-
-class MethodSample {
-  private:
-    u64 _samples;
-    u64 _counter;
-    ASGCT_CallFrame _method;
-
-  public:
-    static int comparator(const void* s1, const void* s2) {
-        return cmp64((*(MethodSample**)s2)->_counter, (*(MethodSample**)s1)->_counter);
-    }
-
-    friend class Profiler;
-};
-
-
-typedef jboolean JNICALL (*NativeLoadLibraryFunc)(JNIEnv*, jobject, jstring, jboolean);
+class FrameName;
 
 enum State {
     IDLE,
@@ -95,89 +71,104 @@ class Profiler {
   private:
     Mutex _state_lock;
     State _state;
+    Trap _begin_trap;
+    Trap _end_trap;
     Mutex _thread_names_lock;
+    // TODO: single map?
     std::map<int, std::string> _thread_names;
+    std::map<int, jlong> _thread_ids;
+    Dictionary _class_map;
+    Dictionary _symbol_map;
+    ThreadFilter _thread_filter;
+    CallTraceStorage _call_trace_storage;
     FlightRecorder _jfr;
     Engine* _engine;
+    int _events;
     time_t _start_time;
 
     u64 _total_samples;
-    u64 _total_counter;
     u64 _failures[ASGCT_FAILURE_TYPES];
-    u64 _hashes[MAX_CALLTRACES];
-    CallTraceSample _traces[MAX_CALLTRACES];
-    MethodSample _methods[MAX_CALLTRACES];
 
     SpinLock _locks[CONCURRENCY_LEVEL];
     CallTraceBuffer* _calltrace_buffer[CONCURRENCY_LEVEL];
-    ASGCT_CallFrame* _frame_buffer;
-    int _frame_buffer_size;
     int _max_stack_depth;
-    volatile int _frame_buffer_index;
-    bool _frame_buffer_overflow;
-    bool _threads;
+    int _safe_mode;
+    CStack _cstack;
+    bool _add_thread_frame;
+    bool _update_thread_names;
     volatile bool _thread_events_state;
 
     SpinLock _jit_lock;
-    const void* _jit_min_address;
-    const void* _jit_max_address;
+    SpinLock _stubs_lock;
     CodeCache _java_methods;
     NativeCodeCache _runtime_stubs;
     NativeCodeCache* _native_libs[MAX_NATIVE_LIBS];
     volatile int _native_lib_count;
 
+    // Support for intercepting NativeLibrary.load() / NativeLibraries.load()
     JNINativeMethod _load_method;
-    NativeLoadLibraryFunc _original_NativeLibrary_load;
+    void* _original_NativeLibrary_load;
+    void* _trapped_NativeLibrary_load;
     static jboolean JNICALL NativeLibraryLoadTrap(JNIEnv* env, jobject self, jstring name, jboolean builtin);
-    void bindNativeLibraryLoad(NativeLoadLibraryFunc entry);
+    static jboolean JNICALL NativeLibrariesLoadTrap(JNIEnv* env, jobject self, jobject lib, jstring name, jboolean builtin, jboolean jni);
+    void bindNativeLibraryLoad(JNIEnv* env, bool enable);
 
-    void* (*_ThreadLocalStorage_thread)();
-    jvmtiError (*_JvmtiEnv_GetStackTrace)(void* self, void* thread, jint start_depth, jint max_frame_count,
-                                          jvmtiFrameInfo* frame_buffer, jint* count_ptr);
+    // Support for intercepting Thread.setNativeName()
+    void* _original_Thread_setNativeName;
+    static void JNICALL ThreadSetNativeNameTrap(JNIEnv* env, jobject self, jstring name);
+    void bindThreadSetNativeName(JNIEnv* env, bool enable);
+
+    void switchNativeMethodTraps(bool enable);
+
+    Error installTraps(const char* begin, const char* end);
+    void uninstallTraps();
+    static void trapHandler(int signo, siginfo_t* siginfo, void* ucontext);
+    void trapHandlerImpl(void* ucontext);
 
     void addJavaMethod(const void* address, int length, jmethodID method);
     void removeJavaMethod(const void* address, jmethodID method);
     void addRuntimeStub(const void* address, int length, const char* name);
-    void updateJitRange(const void* min_address, const void* max_address);
+
+    void onThreadStart(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread);
+    void onThreadEnd(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread);
 
     const char* asgctError(int code);
-    const char* findNativeMethod(const void* address);
-    int getNativeTrace(void* ucontext, ASGCT_CallFrame* frames, int tid, bool* stopped_at_java_frame);
+    u32 getLockIndex(int tid);
+    int getNativeTrace(void* ucontext, ASGCT_CallFrame* frames, int tid);
     int getJavaTraceAsync(void* ucontext, ASGCT_CallFrame* frames, int max_depth);
     int getJavaTraceJvmti(jvmtiFrameInfo* jvmti_frames, ASGCT_CallFrame* frames, int max_depth);
-    int makeEventFrame(ASGCT_CallFrame* frames, jint event_type, jmethodID event);
+    int makeEventFrame(ASGCT_CallFrame* frames, jint event_type, uintptr_t id);
     bool fillTopFrame(const void* pc, ASGCT_CallFrame* frame);
-    bool addressInCode(const void* pc);
-    u64 hashCallTrace(int num_frames, ASGCT_CallFrame* frames);
-    int storeCallTrace(int num_frames, ASGCT_CallFrame* frames, u64 counter);
-    void copyToFrameBuffer(int num_frames, ASGCT_CallFrame* frames, CallTraceSample* trace);
-    u64 hashMethod(jmethodID method);
-    void storeMethod(jmethodID method, jint bci, u64 counter);
-    void initJvmtiFunctions(NativeCodeCache* libjvm);
-    void setThreadName(int tid, const char* name);
+    AddressType getAddressType(instruction_t* pc);
+    void setThreadInfo(int tid, const char* name, jlong java_thread_id);
     void updateThreadName(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread);
-    void updateAllThreadNames();
+    void updateJavaThreadNames();
+    void updateNativeThreadNames();
+    bool excludeTrace(FrameName* fn, CallTrace* trace);
+    void mangle(const char* name, char* buf, size_t size);
     Engine* selectEngine(const char* event_name);
+    Error checkJvmCapabilities();
 
   public:
     static Profiler _instance;
 
     Profiler() :
         _state(IDLE),
+        _begin_trap(),
+        _end_trap(),
+        _thread_filter(),
+        _call_trace_storage(),
         _jfr(),
-        _frame_buffer(NULL),
-        _frame_buffer_size(0),
+        _start_time(0),
         _max_stack_depth(0),
+        _safe_mode(0),
         _thread_events_state(JVMTI_DISABLE),
         _jit_lock(),
-        _jit_min_address((const void*)-1),
-        _jit_max_address((const void*)0),
+        _stubs_lock(),
         _java_methods(),
         _runtime_stubs("[stubs]"),
         _native_lib_count(0),
-        _original_NativeLibrary_load(NULL),
-        _ThreadLocalStorage_thread(NULL),
-        _JvmtiEnv_GetStackTrace(NULL) {
+        _original_NativeLibrary_load(NULL) {
 
         for (int i = 0; i < CONCURRENCY_LEVEL; i++) {
             _calltrace_buffer[i] = NULL;
@@ -185,23 +176,29 @@ class Profiler {
     }
 
     u64 total_samples() { return _total_samples; }
-    u64 total_counter() { return _total_counter; }
     time_t uptime()     { return time(NULL) - _start_time; }
 
+    Dictionary* classMap() { return &_class_map; }
+    ThreadFilter* threadFilter() { return &_thread_filter; }
+
     void run(Arguments& args);
     void runInternal(Arguments& args, std::ostream& out);
     void shutdown(Arguments& args);
+    Error check(Arguments& args);
     Error start(Arguments& args, bool reset);
     Error stop();
     void switchThreadEvents(jvmtiEventMode mode);
-    void dumpSummary(std::ostream& out);
+    void dump(std::ostream& out, Arguments& args);
     void dumpCollapsed(std::ostream& out, Arguments& args);
     void dumpFlameGraph(std::ostream& out, Arguments& args, bool tree);
-    void dumpTraces(std::ostream& out, Arguments& args);
     void dumpFlat(std::ostream& out, Arguments& args);
-    void recordSample(void* ucontext, u64 counter, jint event_type, jmethodID event);
-    NativeCodeCache* jvmLibrary();
-    const void* findSymbol(const char* name);
+    ThreadState getThreadState(void* ucontext);
+    void recordSample(void* ucontext, u64 counter, jint event_type, Event* event);
+
+    void updateSymbols(bool kernel_symbols);
+    const void* resolveSymbol(const char* name);
+    NativeCodeCache* findNativeLibrary(const void* address);
+    const char* findNativeMethod(const void* address);
 
     // CompiledMethodLoad is also needed to enable DebugNonSafepoints info by default
     static void JNICALL CompiledMethodLoad(jvmtiEnv* jvmti, jmethodID method,
@@ -222,13 +219,11 @@ class Profiler {
     }
 
     static void JNICALL ThreadStart(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread) {
-        _instance.updateThreadName(jvmti, jni, thread);
-        _instance._engine->onThreadStart();
+        _instance.onThreadStart(jvmti, jni, thread);
     }
 
     static void JNICALL ThreadEnd(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread) {
-        _instance.updateThreadName(jvmti, jni, thread);
-        _instance._engine->onThreadEnd();
+        _instance.onThreadEnd(jvmti, jni, thread);
     }
 
     friend class Recording;

src/spinLock.h

@@ -30,7 +30,7 @@ class SpinLock {
     volatile int _lock;
 
   public:
-    SpinLock() : _lock(0) {
+    SpinLock(int initial_state = 0) : _lock(initial_state) {
     }
 
     void reset() {

src/stackFrame.h

@@ -19,14 +19,17 @@
 
 #include <stdint.h>
 #include <ucontext.h>
+#include "arch.h"
 
 
 class StackFrame {
   private:
     ucontext_t* _ucontext;
 
-    uintptr_t stackAt(int slot) {
-        return ((uintptr_t*)sp())[slot];
+    static bool withinCurrentStack(uintptr_t address) {
+        // Check that the address is not too far from the stack pointer of current context
+        void* real_sp;
+        return address - (uintptr_t)&real_sp <= 0xffff;
     }
 
   public:
@@ -40,10 +43,19 @@ class StackFrame {
         fp() = saved_fp;
     }
 
+    bool validSP() {
+        return withinCurrentStack(sp());
+    }
+
+    uintptr_t stackAt(int slot) {
+        return ((uintptr_t*)sp())[slot];
+    }
+
     uintptr_t& pc();
     uintptr_t& sp();
     uintptr_t& fp();
 
+    uintptr_t retval();
     uintptr_t arg0();
     uintptr_t arg1();
     uintptr_t arg2();
@@ -52,6 +64,19 @@ class StackFrame {
     void ret();
 
     bool pop(bool trust_frame_pointer);
+
+    bool checkInterruptedSyscall();
+
+    // Look that many stack slots for a return address candidate.
+    // 0 = do not use stack snooping heuristics.
+    static int callerLookupSlots();
+
+    // Check if PC looks like a valid return address (i.e. the previous instruction is a CALL).
+    // It's safe to return false to skip return address heuristics.
+    static bool isReturnAddress(instruction_t* pc);
+
+    // Check if PC points to a syscall instruction
+    static bool isSyscall(instruction_t* pc);
 };
 
 #endif // _STACKFRAME_H

src/stackFrame_aarch64.cpp

@@ -19,6 +19,7 @@
 
 #if defined(__aarch64__)
 
+#include <errno.h>
 #include "stackFrame.h"
 
 
@@ -37,6 +38,10 @@ uintptr_t& StackFrame::fp() {
     return (uintptr_t&)_ucontext->uc_mcontext.regs[REG_FP];
 }
 
+uintptr_t StackFrame::retval() {
+    return (uintptr_t)_ucontext->uc_mcontext.regs[0];
+}
+
 uintptr_t StackFrame::arg0() {
     return (uintptr_t)_ucontext->uc_mcontext.regs[0];
 }
@@ -72,4 +77,21 @@ bool StackFrame::pop(bool trust_frame_pointer) {
     return true;
 }
 
+bool StackFrame::checkInterruptedSyscall() {
+    return retval() == (uintptr_t)-EINTR;
+}
+
+int StackFrame::callerLookupSlots() {
+    return 0;
+}
+
+bool StackFrame::isReturnAddress(instruction_t* pc) {
+    return false;
+}
+
+bool StackFrame::isSyscall(instruction_t* pc) {
+    // svc #0
+    return *pc == 0xd4000001;
+}
+
 #endif // defined(__aarch64__)

src/stackFrame_arm.cpp

@@ -16,6 +16,7 @@
 
 #if defined(__arm__) || defined(__thumb__)
 
+#include <errno.h>
 #include "stackFrame.h"
 
 
@@ -31,6 +32,10 @@ uintptr_t& StackFrame::fp() {
     return (uintptr_t&)_ucontext->uc_mcontext.arm_fp;
 }
 
+uintptr_t StackFrame::retval() {
+    return (uintptr_t)_ucontext->uc_mcontext.arm_r0;
+}
+
 uintptr_t StackFrame::arg0() {
     return (uintptr_t)_ucontext->uc_mcontext.arm_r0;
 }
@@ -55,4 +60,21 @@ bool StackFrame::pop(bool trust_frame_pointer) {
     return false;
 }
 
+bool StackFrame::checkInterruptedSyscall() {
+    return retval() == (uintptr_t)-EINTR;
+}
+
+int StackFrame::callerLookupSlots() {
+    return 0;
+}
+
+bool StackFrame::isReturnAddress(instruction_t* pc) {
+    return false;
+}
+
+bool StackFrame::isSyscall(instruction_t* pc) {
+    // swi #0
+    return *pc == 0xef000000;
+}
+
 #endif // defined(__arm__) || defined(__thumb__)

src/stackFrame_i386.cpp

@@ -16,6 +16,7 @@
 
 #ifdef __i386__
 
+#include <errno.h>
 #include "stackFrame.h"
 
 
@@ -31,6 +32,10 @@ uintptr_t& StackFrame::fp() {
     return (uintptr_t&)_ucontext->uc_mcontext.gregs[REG_EBP];
 }
 
+uintptr_t StackFrame::retval() {
+    return (uintptr_t)_ucontext->uc_mcontext.gregs[REG_EAX];
+}
+
 uintptr_t StackFrame::arg0() {
     return stackAt(1);
 }
@@ -52,31 +57,43 @@ void StackFrame::ret() {
     sp() += 4;
 }
 
-
-static inline bool withinCurrentStack(uintptr_t value) {
-    // Check that value is not too far from stack pointer of current context
-    void* real_sp;
-    return value - (uintptr_t)&real_sp <= 0xffff;
-}
-
 bool StackFrame::pop(bool trust_frame_pointer) {
-    if (!withinCurrentStack(sp())) {
-        return false;
-    }
-
     if (trust_frame_pointer && withinCurrentStack(fp())) {
         sp() = fp() + 8;
         fp() = stackAt(-2);
         pc() = stackAt(-1);
+        return true;
     } else if (fp() == sp() || withinCurrentStack(stackAt(0))) {
         fp() = stackAt(0);
         pc() = stackAt(1);
         sp() += 8;
-    } else {
-        pc() = stackAt(0);
-        sp() += 4;
+        return true;
     }
-    return true;
+    return false;
+}
+
+bool StackFrame::checkInterruptedSyscall() {
+    return retval() == (uintptr_t)-EINTR;
+}
+
+int StackFrame::callerLookupSlots() {
+    return 7;
+}
+
+bool StackFrame::isReturnAddress(instruction_t* pc) {
+    if (pc[-5] == 0xe8) {
+        // call rel32
+        return true;
+    } else if (pc[-2] == 0xff && ((pc[-1] & 0xf0) == 0xd0 || (pc[-1] & 0xf0) == 0x10)) {
+        // call reg or call [reg]
+        return true;
+    }
+    return false;
+}
+
+bool StackFrame::isSyscall(instruction_t* pc) {
+    // int 0x80
+    return pc[0] == 0xcd && pc[1] == 0x80;
 }
 
 #endif // __i386__

src/stackFrame_x64.cpp

@@ -16,6 +16,8 @@
 
 #ifdef __x86_64__
 
+#include <errno.h>
+#include <sys/syscall.h>
 #include "stackFrame.h"
 
 
@@ -38,6 +40,10 @@ uintptr_t& StackFrame::fp() {
     return (uintptr_t&)REG(REG_RBP, __rbp);
 }
 
+uintptr_t StackFrame::retval() {
+    return (uintptr_t)REG(REG_RAX, __rax);
+}
+
 uintptr_t StackFrame::arg0() {
     return (uintptr_t)REG(REG_RDI, __rdi);
 }
@@ -60,12 +66,6 @@ void StackFrame::ret() {
 }
 
 
-static inline bool withinCurrentStack(uintptr_t value) {
-    // Check that value is not too far from stack pointer of current context
-    void* real_sp;
-    return value - (uintptr_t)&real_sp <= 0xffff;
-}
-
 static inline bool isFramePrologueEpilogue(uintptr_t pc) {
     if (pc & 0xfff) {
         // Make sure we are not at the page boundary, so that reading [pc - 1] is safe
@@ -91,23 +91,66 @@ static inline bool isFramePrologueEpilogue(uintptr_t pc) {
 }
 
 bool StackFrame::pop(bool trust_frame_pointer) {
-    if (!withinCurrentStack(sp())) {
-        return false;
-    }
-
     if (trust_frame_pointer && withinCurrentStack(fp())) {
         sp() = fp() + 16;
         fp() = stackAt(-2);
         pc() = stackAt(-1);
+        return true;
     } else if (fp() == sp() || withinCurrentStack(stackAt(0)) || isFramePrologueEpilogue(pc())) {
         fp() = stackAt(0);
         pc() = stackAt(1);
         sp() += 16;
-    } else {
-        pc() = stackAt(0);
-        sp() += 8;
+        return true;
     }
-    return true;
+    return false;
+}
+
+bool StackFrame::checkInterruptedSyscall() {
+#ifdef __APPLE__
+    // We are not interested in syscalls that do not check error code, e.g. semaphore_wait_trap
+    if (*(instruction_t*)pc() == 0xc3) {
+        return true;
+    }
+    // If CF is set, the error code is in low byte of eax,
+    // some other syscalls (ulock_wait) do not set CF when interrupted
+    if (REG(REG_EFL, __rflags) & 1) {
+        return (retval() & 0xff) == EINTR || (retval() & 0xff) == ETIMEDOUT;
+    } else {
+        return retval() == (uintptr_t)-EINTR; 
+    }
+#else
+    if (retval() == (uintptr_t)-EINTR) {
+        // Workaround for JDK-8237858: restart the interrupted poll() manually.
+        // Check if the previous instruction is mov eax, SYS_poll with infinite timeout
+        if (arg2() == (uintptr_t)-1) {
+            uintptr_t pc = this->pc();
+            if ((pc & 0xfff) >= 7 && *(unsigned char*)(pc - 7) == 0xb8 && *(int*)(pc - 6) == SYS_poll) {
+                this->pc() = pc - 7;
+            }
+        }
+        return true;
+    }
+    return false;
+#endif
+}
+
+int StackFrame::callerLookupSlots() {
+    return 7;
+}
+
+bool StackFrame::isReturnAddress(instruction_t* pc) {
+    if (pc[-5] == 0xe8) {
+        // call rel32
+        return true;
+    } else if (pc[-2] == 0xff && ((pc[-1] & 0xf0) == 0xd0 || (pc[-1] & 0xf0) == 0x10)) {
+        // call reg or call [reg]
+        return true;
+    }
+    return false;
+}
+
+bool StackFrame::isSyscall(instruction_t* pc) {
+    return pc[0] == 0x0f && pc[1] == 0x05;
 }
 
 #endif // __x86_64__

src/symbols.h

@@ -18,7 +18,6 @@
 #define _SYMBOLS_H
 
 #include <set>
-#include "arch.h"
 #include "codeCache.h"
 #include "mutex.h"
 
@@ -27,11 +26,15 @@ class Symbols {
   private:
     static Mutex _parse_lock;
     static std::set<const void*> _parsed_libraries;
-
-    static void parseKernelSymbols(NativeCodeCache* cc);
+    static bool _have_kernel_symbols;
 
   public:
-    static void parseLibraries(NativeCodeCache** array, volatile int& count, int size);
+    static void parseKernelSymbols(NativeCodeCache* cc);
+    static void parseLibraries(NativeCodeCache** array, volatile int& count, int size, bool kernel_symbols);
+
+    static bool haveKernelSymbols() {
+        return _have_kernel_symbols;
+    }
 };
 
 #endif // _SYMBOLS_H

src/symbols_linux.cpp

@@ -16,12 +16,14 @@
 
 #ifdef __linux__
 
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
 #include <elf.h>
+#include <errno.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <linux/limits.h>
@@ -29,6 +31,7 @@
 #include <iostream>
 #include <string>
 #include "symbols.h"
+#include "arch.h"
 
 
 class SymbolDesc {
@@ -87,12 +90,16 @@ typedef Elf64_Ehdr ElfHeader;
 typedef Elf64_Shdr ElfSection;
 typedef Elf64_Nhdr ElfNote;
 typedef Elf64_Sym  ElfSymbol;
+typedef Elf64_Rel  ElfRelocation;
+#define ELF_R_SYM  ELF64_R_SYM
 #else
 const unsigned char ELFCLASS_SUPPORTED = ELFCLASS32;
 typedef Elf32_Ehdr ElfHeader;
 typedef Elf32_Shdr ElfSection;
 typedef Elf32_Nhdr ElfNote;
 typedef Elf32_Sym  ElfSymbol;
+typedef Elf32_Rel  ElfRelocation;
+#define ELF_R_SYM  ELF32_R_SYM
 #endif // __LP64__
 
 
@@ -133,6 +140,7 @@ class ElfParser {
     bool loadSymbolsUsingBuildId();
     bool loadSymbolsUsingDebugLink();
     void loadSymbolTable(ElfSection* symtab);
+    void addRelocationSymbols(ElfSection* reltab, const char* plt);
 
   public:
     static bool parseFile(NativeCodeCache* cc, const char* base, const char* file_name, bool use_debug);
@@ -165,7 +173,14 @@ bool ElfParser::parseFile(NativeCodeCache* cc, const char* base, const char* fil
     void* addr = mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, 0);
     close(fd);
 
-    if (addr != NULL) {
+    if (addr == MAP_FAILED) {
+        if (strcmp(file_name, "/") == 0) {
+            // https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1843018
+            fprintf(stderr, "Could not parse symbols due to the OS bug\n");
+        } else {
+            fprintf(stderr, "Could not parse symbols from %s: %s\n", file_name, strerror(errno));
+        }
+    } else {
         ElfParser elf(cc, base, addr, file_name);
         elf.loadSymbols(use_debug);
         munmap(addr, length);
@@ -187,13 +202,13 @@ void ElfParser::loadSymbols(bool use_debug) {
     ElfSection* section = findSection(SHT_SYMTAB, ".symtab");
     if (section != NULL) {
         loadSymbolTable(section);
-        return;
+        goto loaded;
     }
 
     // Try to load symbols from an external debuginfo library
     if (use_debug) {
         if (loadSymbolsUsingBuildId() || loadSymbolsUsingDebugLink()) {
-            return;
+            goto loaded;
         }
     }
 
@@ -202,6 +217,19 @@ void ElfParser::loadSymbols(bool use_debug) {
     if (section != NULL) {
         loadSymbolTable(section);
     }
+
+loaded:
+    // Synthesize names for PLT stubs
+    if (use_debug) {
+        ElfSection* plt = findSection(SHT_PROGBITS, ".plt");
+        ElfSection* reltab = findSection(SHT_RELA, ".rela.plt");
+        if (reltab == NULL) {
+            reltab = findSection(SHT_REL, ".rel.plt");
+        }
+        if (plt != NULL && reltab != NULL) {
+            addRelocationSymbols(reltab, _base + plt->sh_offset + PLT_HEADER_SIZE);
+        }
+    }
 }
 
 // Load symbols from /usr/lib/debug/.build-id/ab/cdef1234.debug, where abcdef1234 is Build ID
@@ -284,9 +312,37 @@ void ElfParser::loadSymbolTable(ElfSection* symtab) {
     }
 }
 
+void ElfParser::addRelocationSymbols(ElfSection* reltab, const char* plt) {
+    ElfSection* symtab = section(reltab->sh_link);
+    const char* symbols = at(symtab);
+
+    ElfSection* strtab = section(symtab->sh_link);
+    const char* strings = at(strtab);
+
+    const char* relocations = at(reltab);
+    const char* relocations_end = relocations + reltab->sh_size;
+    for (; relocations < relocations_end; relocations += reltab->sh_entsize) {
+        ElfRelocation* r = (ElfRelocation*)relocations;
+        ElfSymbol* sym = (ElfSymbol*)(symbols + ELF_R_SYM(r->r_info) * symtab->sh_entsize);
+
+        char name[256];
+        if (sym->st_name == 0) {
+            strcpy(name, "@plt");
+        } else {
+            const char* sym_name = strings + sym->st_name;
+            snprintf(name, sizeof(name), "%s%cplt", sym_name, sym_name[0] == '_' && sym_name[1] == 'Z' ? '.' : '@');
+            name[sizeof(name) - 1] = 0;
+        }
+
+        _cc->add(plt, PLT_ENTRY_SIZE, name);
+        plt += PLT_ENTRY_SIZE;
+    }
+}
+
 
 Mutex Symbols::_parse_lock;
 std::set<const void*> Symbols::_parsed_libraries;
+bool Symbols::_have_kernel_symbols = false;
 
 void Symbols::parseKernelSymbols(NativeCodeCache* cc) {
     std::ifstream maps("/proc/kallsyms");
@@ -300,20 +356,26 @@ void Symbols::parseKernelSymbols(NativeCodeCache* cc) {
             const char* addr = symbol.addr();
             if (addr != NULL) {
                 cc->add(addr, 0, symbol.name());
+                _have_kernel_symbols = true;
             }
         }
     }
 }
 
-void Symbols::parseLibraries(NativeCodeCache** array, volatile int& count, int size) {
+void Symbols::parseLibraries(NativeCodeCache** array, volatile int& count, int size, bool kernel_symbols) {
     MutexLocker ml(_parse_lock);
 
-    if (count == 0) {
+    if (kernel_symbols && !haveKernelSymbols()) {
         NativeCodeCache* cc = new NativeCodeCache("[kernel]");
         parseKernelSymbols(cc);
-        cc->sort();
-        array[count] = cc;
-        atomicInc(count);
+
+        if (haveKernelSymbols()) {
+            cc->sort();
+            array[count] = cc;
+            atomicInc(count);
+        } else {
+            delete cc;
+        }
     }
 
     std::ifstream maps("/proc/self/maps");

src/symbols_macos.cpp

@@ -16,6 +16,8 @@
 
 #ifdef __APPLE__
 
+#include <stdio.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <sys/mman.h>
@@ -25,6 +27,7 @@
 #include <mach-o/fat.h>
 #include <mach-o/nlist.h>
 #include "symbols.h"
+#include "arch.h"
 
 
 class MachOParser {
@@ -113,7 +116,9 @@ class MachOParser {
         void* addr = mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, 0);
         close(fd);
 
-        if (addr != NULL) {
+        if (addr == MAP_FAILED) {
+            fprintf(stderr, "Could not parse symbols from %s: %s\n", file_name, strerror(errno));
+        } else {
             MachOParser parser(cc, image_base);
             parser.parse((mach_header*)addr);
             munmap(addr, length);
@@ -124,11 +129,12 @@ class MachOParser {
 
 Mutex Symbols::_parse_lock;
 std::set<const void*> Symbols::_parsed_libraries;
+bool Symbols::_have_kernel_symbols = false;
 
 void Symbols::parseKernelSymbols(NativeCodeCache* cc) {
 }
 
-void Symbols::parseLibraries(NativeCodeCache** array, volatile int& count, int size) {
+void Symbols::parseLibraries(NativeCodeCache** array, volatile int& count, int size, bool kernel_symbols) {
     MutexLocker ml(_parse_lock);
     uint32_t images = _dyld_image_count();
 

src/threadFilter.cpp

@@ -0,0 +1,127 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "threadFilter.h"
+#include "os.h"
+
+    
+ThreadFilter::ThreadFilter() {
+    memset(_bitmap, 0, sizeof(_bitmap));
+    _bitmap[0] = (u32*)OS::safeAlloc(BITMAP_SIZE);
+
+    _enabled = false;
+    _size = 0;
+}
+
+ThreadFilter::~ThreadFilter() {
+    for (int i = 0; i < MAX_BITMAPS; i++) {
+        if (_bitmap[i] != NULL) {
+            OS::safeFree(_bitmap[i], BITMAP_SIZE);
+        }
+    }
+}
+
+void ThreadFilter::init(const char* filter) {
+    if (filter == NULL) {
+        _enabled = false;
+        return;
+    }
+
+    char* end;
+    do {
+        int id = strtol(filter, &end, 0);
+        if (id <= 0) {
+            break;
+        }
+
+        if (*end == '-') {
+            int to = strtol(end + 1, &end, 0);
+            while (id <= to) {
+                add(id++);
+            }
+        } else {
+            add(id);
+        }
+
+        filter = end + 1;
+    } while (*end);
+
+    _enabled = true;
+}
+
+void ThreadFilter::clear() {
+    for (int i = 0; i < MAX_BITMAPS; i++) {
+        if (_bitmap[i] != NULL) {
+            memset(_bitmap[i], 0, BITMAP_SIZE);
+        }
+    }
+    _size = 0;
+}
+
+bool ThreadFilter::accept(int thread_id) {
+    u32* b = bitmap(thread_id);
+    return b != NULL && (word(b, thread_id) & (1 << (thread_id & 0x1f)));
+}
+
+void ThreadFilter::add(int thread_id) {
+    u32* b = bitmap(thread_id);
+    if (b == NULL) {
+        b = (u32*)OS::safeAlloc(BITMAP_SIZE);
+        u32* oldb = __sync_val_compare_and_swap(&_bitmap[(u32)thread_id / BITMAP_CAPACITY], NULL, b);
+        if (oldb != NULL) {
+            OS::safeFree(b, BITMAP_SIZE);
+            b = oldb;
+        }
+    }
+
+    u32 bit = 1 << (thread_id & 0x1f);
+    if (!(__sync_fetch_and_or(&word(b, thread_id), bit) & bit)) {
+        atomicInc(_size);
+    }
+}
+
+void ThreadFilter::remove(int thread_id) {
+    u32* b = bitmap(thread_id);
+    if (b == NULL) {
+        return;
+    }
+
+    u32 bit = 1 << (thread_id & 0x1f);
+    if (__sync_fetch_and_and(&word(b, thread_id), ~bit) & bit) {
+        atomicInc(_size, -1);
+    }
+}
+
+void ThreadFilter::collect(std::vector<int>& v) {
+    for (int i = 0; i < MAX_BITMAPS; i++) {
+        u32* b = _bitmap[i];
+        if (b != NULL) {
+            int start_id = i * BITMAP_CAPACITY;
+            for (int j = 0; j < BITMAP_SIZE / sizeof(u32); j++) {
+                u32 word = b[j];
+                if (word) {
+                    for (int bit = 0; bit < 32; bit++) {
+                        if (word & (1 << bit)) {
+                            v.push_back(start_id + j * 32 + bit);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

src/threadFilter.h

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _THREADFILTER_H
+#define _THREADFILTER_H
+
+#include <vector>
+#include "arch.h"
+
+
+// The size of thread ID bitmap in bytes. Must be at least 64K to allow mmap()
+const u32 BITMAP_SIZE = 65536;
+// How many thread IDs one bitmap can hold
+const u32 BITMAP_CAPACITY = BITMAP_SIZE * 8;
+// Total number of bitmaps required to hold the entire range of thread IDs
+const u32 MAX_BITMAPS = (1 << 31) / BITMAP_CAPACITY;
+
+
+// ThreadFilter query operations must be lock-free and signal-safe;
+// update operations are mostly lock-free, except rare bitmap allocations
+class ThreadFilter {
+  private:
+    u32* _bitmap[MAX_BITMAPS];
+    bool _enabled;
+    volatile int _size;
+
+    u32* bitmap(int thread_id) {
+        return _bitmap[(u32)thread_id / BITMAP_CAPACITY];
+    }
+
+    u32& word(u32* bitmap, int thread_id) {
+        return bitmap[((u32)thread_id % BITMAP_CAPACITY) >> 5];
+    }
+
+  public:
+    ThreadFilter();
+    ~ThreadFilter();
+
+    bool enabled() {
+        return _enabled;
+    }
+
+    int size() {
+        return _size;
+    }
+
+    void init(const char* filter);
+    void clear();
+
+    bool accept(int thread_id);
+    void add(int thread_id);
+    void remove(int thread_id);
+
+    void collect(std::vector<int>& v);
+};
+
+#endif // _THREADFILTER_H

src/trap.cpp

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <unistd.h>
+#include <sys/mman.h>
+#include "trap.h"
+
+
+bool Trap::assign(const void* address) {
+    uintptr_t entry = (uintptr_t)address;
+    if (entry == 0) {
+        _entry = 0;
+        return true;
+    }
+
+#if defined(__arm__) || defined(__thumb__)
+    if (entry & 1) {
+        entry ^= 1;
+        _breakpoint_insn = BREAKPOINT_THUMB;
+    }
+#endif
+
+    if (entry != _entry) {
+        // Make the entry point writable, so we can rewrite instructions
+        long page_size = sysconf(_SC_PAGESIZE);
+        if (mprotect((void*)(entry & -page_size), page_size, PROT_READ | PROT_WRITE | PROT_EXEC) != 0) {
+            return false;
+        }
+        _entry = entry;
+        _saved_insn = *(instruction_t*)entry;
+    }
+
+    return true;
+}
+
+// Insert breakpoint at the very first instruction
+void Trap::install() {
+    if (_entry) {
+        *(instruction_t*)_entry = _breakpoint_insn;
+        flushCache(_entry);
+    }
+}
+
+// Clear breakpoint - restore the original instruction
+void Trap::uninstall() {
+    if (_entry) {
+        *(instruction_t*)_entry = _saved_insn;
+        flushCache(_entry);
+    }
+}

src/trap.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2020 Andrei Pangin
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _TRAP_H
+#define _TRAP_H
+
+#include <stdint.h>
+#include "arch.h"
+
+
+class Trap {
+  private:
+    uintptr_t _entry;
+    instruction_t _breakpoint_insn;
+    instruction_t _saved_insn;
+
+  public:
+    Trap() : _entry(0), _breakpoint_insn(BREAKPOINT) {
+    }
+
+    uintptr_t entry() {
+        return _entry;
+    }
+
+    bool covers(uintptr_t pc) {
+        // PC points either to BREAKPOINT instruction or to the next one
+        return pc - _entry <= sizeof(instruction_t);
+    }
+
+    bool assign(const void* address);
+    void install();
+    void uninstall();
+};
+
+#endif // _TRAP_H

src/vmEntry.cpp

@@ -16,20 +16,30 @@
 
 #include <fstream>
 #include <dlfcn.h>
+#include <stdlib.h>
+#include <string.h>
 #include "vmEntry.h"
 #include "arguments.h"
+#include "javaApi.h"
 #include "os.h"
 #include "profiler.h"
+#include "instrument.h"
 #include "lockTracer.h"
+#include "vmStructs.h"
 
 
 static Arguments _agent_args;
 
 JavaVM* VM::_vm;
 jvmtiEnv* VM::_jvmti = NULL;
+int VM::_hotspot_version = 0;
 void* VM::_libjvm;
 void* VM::_libjava;
 AsyncGetCallTrace VM::_asyncGetCallTrace;
+JVM_GetManagement VM::_getManagement;
+jvmtiError (JNICALL *VM::_orig_RedefineClasses)(jvmtiEnv*, jint, const jvmtiClassDefinition*);
+jvmtiError (JNICALL *VM::_orig_RetransformClasses)(jvmtiEnv*, jint, const jclass* classes);
+volatile int VM::_in_redefine_classes = 0;
 
 
 void VM::init(JavaVM* vm, bool attach) {
@@ -38,8 +48,47 @@ void VM::init(JavaVM* vm, bool attach) {
     _vm = vm;
     _vm->GetEnv((void**)&_jvmti, JVMTI_VERSION_1_0);
 
+    char* prop;
+    if (_jvmti->GetSystemProperty("java.vm.name", &prop) == 0) {
+        bool is_hotspot = strstr(prop, "OpenJDK") != NULL ||
+                          strstr(prop, "HotSpot") != NULL ||
+                          strstr(prop, "GraalVM") != NULL;
+        _jvmti->Deallocate((unsigned char*)prop);
+
+        if (is_hotspot && _jvmti->GetSystemProperty("java.vm.version", &prop) == 0) {
+            if (strncmp(prop, "25.", 3) == 0) {
+                _hotspot_version = 8;
+            } else if (strncmp(prop, "24.", 3) == 0) {
+                _hotspot_version = 7;
+            } else if (strncmp(prop, "20.", 3) == 0) {
+                _hotspot_version = 6;
+            } else if ((_hotspot_version = atoi(prop)) < 9) {
+                _hotspot_version = 9;
+            }
+            _jvmti->Deallocate((unsigned char*)prop);
+        }
+
+        if (is_hotspot) {
+            JVMTIFunctions* functions = *(JVMTIFunctions**)_jvmti;
+            _orig_RedefineClasses = functions->RedefineClasses;
+            _orig_RetransformClasses = functions->RetransformClasses;
+            functions->RedefineClasses = RedefineClassesHook;
+            functions->RetransformClasses = RetransformClassesHook;
+        }
+    }
+
+    _libjvm = getLibraryHandle("libjvm.so");
+    _asyncGetCallTrace = (AsyncGetCallTrace)dlsym(_libjvm, "AsyncGetCallTrace");
+    _getManagement = (JVM_GetManagement)dlsym(_libjvm, "JVM_GetManagement");
+
+    if (attach) {
+        ready();
+    }
+
     jvmtiCapabilities capabilities = {0};
     capabilities.can_generate_all_class_hook_events = 1;
+    capabilities.can_retransform_classes = 1;
+    capabilities.can_retransform_any_class = 1;
     capabilities.can_get_bytecodes = 1;
     capabilities.can_get_constant_pool = 1;
     capabilities.can_get_source_file_name = 1;
@@ -54,6 +103,7 @@ void VM::init(JavaVM* vm, bool attach) {
     callbacks.VMDeath = VMDeath;
     callbacks.ClassLoad = ClassLoad;
     callbacks.ClassPrepare = ClassPrepare;
+    callbacks.ClassFileLoadHook = Instrument::ClassFileLoadHook;
     callbacks.CompiledMethodLoad = Profiler::CompiledMethodLoad;
     callbacks.CompiledMethodUnload = Profiler::CompiledMethodUnload;
     callbacks.DynamicCodeGenerated = Profiler::DynamicCodeGenerated;
@@ -71,17 +121,24 @@ void VM::init(JavaVM* vm, bool attach) {
     _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_COMPILED_METHOD_UNLOAD, NULL);
     _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_DYNAMIC_CODE_GENERATED, NULL);
 
-    _libjvm = getLibraryHandle("libjvm.so");
-    _libjava = getLibraryHandle("libjava.so");
-    _asyncGetCallTrace = (AsyncGetCallTrace)dlsym(_libjvm, "AsyncGetCallTrace");
-
     if (attach) {
-        loadAllMethodIDs(_jvmti);
+        loadAllMethodIDs(jvmti(), jni());
         _jvmti->GenerateEvents(JVMTI_EVENT_DYNAMIC_CODE_GENERATED);
         _jvmti->GenerateEvents(JVMTI_EVENT_COMPILED_METHOD_LOAD);
     }
 }
 
+// Run late initialization when JVM is ready
+void VM::ready() {
+    Profiler::_instance.updateSymbols(false);
+    NativeCodeCache* libjvm = Profiler::_instance.findNativeLibrary((const void*)_asyncGetCallTrace);
+    if (libjvm != NULL) {
+        VMStructs::init(libjvm);
+    }
+
+    _libjava = getLibraryHandle("libjava.so");
+}
+
 void* VM::getLibraryHandle(const char* name) {
     if (!OS::isJavaLibraryVisible()) {
         void* handle = dlopen(name, RTLD_LAZY);
@@ -93,7 +150,22 @@ void* VM::getLibraryHandle(const char* name) {
     return RTLD_DEFAULT;
 }
 
-void VM::loadMethodIDs(jvmtiEnv* jvmti, jclass klass) {
+void VM::loadMethodIDs(jvmtiEnv* jvmti, JNIEnv* jni, jclass klass) {
+    if (VMStructs::hasClassLoaderData()) {
+        VMKlass* vmklass = VMKlass::fromJavaClass(jni, klass);
+        int method_count = vmklass->methodCount();
+        if (method_count > 0) {
+            ClassLoaderData* cld = vmklass->classLoaderData();
+            cld->lock();
+            // Workaround for JVM bug: preallocate space for jmethodIDs
+            // at the beginning of the list (rather than at the end)
+            for (int i = 0; i < method_count; i += MethodList::SIZE) {
+                *cld->methodList() = new MethodList(*cld->methodList());
+            }
+            cld->unlock();
+        }
+    }
+
     jint method_count;
     jmethodID* methods;
     if (jvmti->GetClassMethods(klass, &method_count, &methods) == 0) {
@@ -101,19 +173,21 @@ void VM::loadMethodIDs(jvmtiEnv* jvmti, jclass klass) {
     }
 }
 
-void VM::loadAllMethodIDs(jvmtiEnv* jvmti) {
+void VM::loadAllMethodIDs(jvmtiEnv* jvmti, JNIEnv* jni) {
     jint class_count;
     jclass* classes;
     if (jvmti->GetLoadedClasses(&class_count, &classes) == 0) {
         for (int i = 0; i < class_count; i++) {
-            loadMethodIDs(jvmti, classes[i]);
+            loadMethodIDs(jvmti, jni, classes[i]);
         }
         jvmti->Deallocate((unsigned char*)classes);
     }
 }
 
 void JNICALL VM::VMInit(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread) {
-    loadAllMethodIDs(jvmti);
+    ready();
+    loadAllMethodIDs(jvmti, jni);
+
     // Delayed start of profiler if agent has been loaded at VM bootstrap
     Profiler::_instance.run(_agent_args);
 }
@@ -122,6 +196,38 @@ void JNICALL VM::VMDeath(jvmtiEnv* jvmti, JNIEnv* jni) {
     Profiler::_instance.shutdown(_agent_args);
 }
 
+jvmtiError VM::RedefineClassesHook(jvmtiEnv* jvmti, jint class_count, const jvmtiClassDefinition* class_definitions) {
+    atomicInc(_in_redefine_classes);
+    jvmtiError result = _orig_RedefineClasses(jvmti, class_count, class_definitions);
+
+    // jmethodIDs are invalidated after RedefineClasses
+    JNIEnv* env = jni();
+    for (int i = 0; i < class_count; i++) {
+        if (class_definitions[i].klass != NULL) {
+            loadMethodIDs(jvmti, env, class_definitions[i].klass);
+        }
+    }
+
+    atomicInc(_in_redefine_classes, -1);
+    return result;
+}
+
+jvmtiError VM::RetransformClassesHook(jvmtiEnv* jvmti, jint class_count, const jclass* classes) {
+    atomicInc(_in_redefine_classes);
+    jvmtiError result = _orig_RetransformClasses(jvmti, class_count, classes);
+
+    // jmethodIDs are invalidated after RetransformClasses
+    JNIEnv* env = jni();
+    for (int i = 0; i < class_count; i++) {
+        if (classes[i] != NULL) {
+            loadMethodIDs(jvmti, env, classes[i]);
+        }
+    }
+
+    atomicInc(_in_redefine_classes, -1);
+    return result;
+}
+
 
 extern "C" JNIEXPORT jint JNICALL
 Agent_OnLoad(JavaVM* vm, char* options, void* reserved) {
@@ -159,5 +265,6 @@ Agent_OnAttach(JavaVM* vm, char* options, void* reserved) {
 extern "C" JNIEXPORT jint JNICALL
 JNI_OnLoad(JavaVM* vm, void* reserved) {
     VM::init(vm, true);
+    JavaAPI::registerNatives(VM::jvmti(), VM::jni());
     return JNI_VERSION_1_6;
 }

src/vmEntry.h

@@ -20,13 +20,22 @@
 #include <jvmti.h>
 
 
+#if __GNUC__ == 4
+#  undef JNIEXPORT
+#  define JNIEXPORT __attribute__((visibility("default")))
+#endif
+
+
 // Denotes ASGCT_CallFrame where method_id has special meaning (not jmethodID)
 enum ASGCT_CallFrameType {
-    BCI_NATIVE_FRAME        = -10,  // method_id is native function name (char*)
-    BCI_SYMBOL              = -11,  // method_id is VMSymbol*
-    BCI_SYMBOL_OUTSIDE_TLAB = -12,  // VMSymbol* specifically for allocations outside TLAB
-    BCI_THREAD_ID           = -13,  // method_id designates a thread
-    BCI_ERROR               = -14,  // method_id is error string
+    BCI_NATIVE_FRAME        = -10,  // native function name (char*)
+    BCI_ALLOC               = -11,  // name of the allocated class
+    BCI_ALLOC_OUTSIDE_TLAB  = -12,  // name of the class allocated outside TLAB
+    BCI_LOCK                = -13,  // class name of the locked object
+    BCI_PARK                = -14,  // class name of the park() blocker
+    BCI_THREAD_ID           = -15,  // method_id designates a thread
+    BCI_ERROR               = -16,  // method_id is an error string
+    BCI_INSTRUMENT          = -17,  // synthetic method_id that should not appear in the call stack
 };
 
 // See hotspot/src/share/vm/prims/forte.cpp
@@ -59,15 +68,35 @@ typedef struct {
 
 typedef void (*AsyncGetCallTrace)(ASGCT_CallTrace*, jint, void*);
 
+typedef struct {
+    void* unused[38];
+    jstring (JNICALL *ExecuteDiagnosticCommand)(JNIEnv*, jstring);
+} VMManagement;
+
+typedef VMManagement* (*JVM_GetManagement)(jint);
+
+typedef struct {
+    void* unused1[86];
+    jvmtiError (JNICALL *RedefineClasses)(jvmtiEnv*, jint, const jvmtiClassDefinition*);
+    void* unused2[64];
+    jvmtiError (JNICALL *RetransformClasses)(jvmtiEnv*, jint, const jclass*);
+} JVMTIFunctions;
+
 
 class VM {
   private:
     static JavaVM* _vm;
     static jvmtiEnv* _jvmti;
+    static JVM_GetManagement _getManagement;
+    static jvmtiError (JNICALL *_orig_RedefineClasses)(jvmtiEnv*, jint, const jvmtiClassDefinition*);
+    static jvmtiError (JNICALL *_orig_RetransformClasses)(jvmtiEnv*, jint, const jclass* classes);
+    static volatile int _in_redefine_classes;
+    static int _hotspot_version;
 
+    static void ready();
     static void* getLibraryHandle(const char* name);
-    static void loadMethodIDs(jvmtiEnv* jvmti, jclass klass);
-    static void loadAllMethodIDs(jvmtiEnv* jvmti);
+    static void loadMethodIDs(jvmtiEnv* jvmti, JNIEnv* jni, jclass klass);
+    static void loadAllMethodIDs(jvmtiEnv* jvmti, JNIEnv* jni);
 
   public:
     static void* _libjvm;
@@ -85,6 +114,18 @@ class VM {
         return _vm->GetEnv((void**)&jni, JNI_VERSION_1_6) == 0 ? jni : NULL;
     }
 
+    static VMManagement* management() {
+        return _getManagement != NULL ? _getManagement(0x20030000) : NULL;
+    }
+
+    static int hotspot_version() {
+        return _hotspot_version;
+    }
+
+    static bool inRedefineClasses() {
+        return _in_redefine_classes > 0;
+    }
+
     static void JNICALL VMInit(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread);
     static void JNICALL VMDeath(jvmtiEnv* jvmti, JNIEnv* jni);
 
@@ -93,8 +134,11 @@ class VM {
     }
 
     static void JNICALL ClassPrepare(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread, jclass klass) {
-        loadMethodIDs(jvmti, klass);
+        loadMethodIDs(jvmti, jni, klass);
     }
+
+    static jvmtiError JNICALL RedefineClassesHook(jvmtiEnv* jvmti, jint class_count, const jvmtiClassDefinition* class_definitions);
+    static jvmtiError JNICALL RetransformClassesHook(jvmtiEnv* jvmti, jint class_count, const jclass* classes);
 };
 
 #endif // _VMENTRY_H

src/vmStructs.cpp

@@ -14,24 +14,51 @@
  * limitations under the License.
  */
 
+#include <pthread.h>
 #include <stdint.h>
 #include <string.h>
 #include "vmStructs.h"
 #include "vmEntry.h"
 
 
+NativeCodeCache* VMStructs::_libjvm = NULL;
+
+bool VMStructs::_has_class_names = false;
+bool VMStructs::_has_class_loader_data = false;
+bool VMStructs::_has_thread_bridge = false;
+bool VMStructs::_has_perm_gen = false;
+
 int VMStructs::_klass_name_offset = -1;
 int VMStructs::_symbol_length_offset = -1;
 int VMStructs::_symbol_length_and_refcount_offset = -1;
 int VMStructs::_symbol_body_offset = -1;
-int VMStructs::_class_klass_offset = -1;
+int VMStructs::_class_loader_data_offset = -1;
+int VMStructs::_methods_offset = -1;
 int VMStructs::_thread_osthread_offset = -1;
+int VMStructs::_thread_anchor_offset = -1;
+int VMStructs::_thread_state_offset = -1;
 int VMStructs::_osthread_id_offset = -1;
-bool VMStructs::_has_perm_gen = false;
-jfieldID VMStructs::_eetop = NULL;
+int VMStructs::_anchor_sp_offset = -1;
+int VMStructs::_anchor_pc_offset = -1;
+int VMStructs::_frame_size_offset = -1;
+int VMStructs::_is_gc_active_offset = -1;
+char* VMStructs::_collected_heap_addr = NULL;
 
-static uintptr_t readSymbol(NativeCodeCache* lib, const char* symbol_name) {
-    const void* symbol = lib->findSymbol(symbol_name);
+jfieldID VMStructs::_eetop;
+jfieldID VMStructs::_tid;
+jfieldID VMStructs::_klass = NULL;
+int VMStructs::_tls_index = -1;
+intptr_t VMStructs::_env_offset;
+
+VMStructs::GetStackTraceFunc VMStructs::_get_stack_trace = NULL;
+VMStructs::UnsafeParkFunc VMStructs::_unsafe_park = NULL;
+VMStructs::FindBlobFunc VMStructs::_find_blob = NULL;
+VMStructs::LockFunc VMStructs::_lock_func;
+VMStructs::LockFunc VMStructs::_unlock_func;
+
+
+uintptr_t VMStructs::readSymbol(const char* symbol_name) {
+    const void* symbol = _libjvm->findSymbol(symbol_name);
     if (symbol == NULL) {
         // Avoid JVM crash in case of missing symbols
         return 0;
@@ -40,16 +67,24 @@ static uintptr_t readSymbol(NativeCodeCache* lib, const char* symbol_name) {
 }
 
 void VMStructs::init(NativeCodeCache* libjvm) {
-    if (available()) {
-        return;
-    }
+    _libjvm = libjvm;
 
-    uintptr_t entry = readSymbol(libjvm, "gHotSpotVMStructs");
-    uintptr_t stride = readSymbol(libjvm, "gHotSpotVMStructEntryArrayStride");
-    uintptr_t type_offset = readSymbol(libjvm, "gHotSpotVMStructEntryTypeNameOffset");
-    uintptr_t field_offset = readSymbol(libjvm, "gHotSpotVMStructEntryFieldNameOffset");
-    uintptr_t offset_offset = readSymbol(libjvm, "gHotSpotVMStructEntryOffsetOffset");
-    uintptr_t address_offset = readSymbol(libjvm, "gHotSpotVMStructEntryAddressOffset");
+    initOffsets();
+    initJvmFunctions();
+
+    JNIEnv* env = VM::jni();
+    initThreadBridge(env);
+    initLogging(env);
+    env->ExceptionClear();
+}
+
+void VMStructs::initOffsets() {
+    uintptr_t entry = readSymbol("gHotSpotVMStructs");
+    uintptr_t stride = readSymbol("gHotSpotVMStructEntryArrayStride");
+    uintptr_t type_offset = readSymbol("gHotSpotVMStructEntryTypeNameOffset");
+    uintptr_t field_offset = readSymbol("gHotSpotVMStructEntryFieldNameOffset");
+    uintptr_t offset_offset = readSymbol("gHotSpotVMStructEntryOffsetOffset");
+    uintptr_t address_offset = readSymbol("gHotSpotVMStructEntryAddressOffset");
 
     if (entry == 0 || stride == 0) {
         return;
@@ -74,18 +109,47 @@ void VMStructs::init(NativeCodeCache* libjvm) {
             } else if (strcmp(field, "_body") == 0) {
                 _symbol_body_offset = *(int*)(entry + offset_offset);
             }
+        } else if (strcmp(type, "InstanceKlass") == 0) {
+            if (strcmp(field, "_class_loader_data") == 0) {
+                _class_loader_data_offset = *(int*)(entry + offset_offset);
+            } else if (strcmp(field, "_methods") == 0) {
+                _methods_offset = *(int*)(entry + offset_offset);
+            }
         } else if (strcmp(type, "java_lang_Class") == 0) {
             if (strcmp(field, "_klass_offset") == 0) {
-                _class_klass_offset = **(int**)(entry + address_offset);
+                int klass_offset = **(int**)(entry + address_offset);
+                _klass = (jfieldID)(uintptr_t)(klass_offset << 2 | 2);
             }
         } else if (strcmp(type, "JavaThread") == 0) {
             if (strcmp(field, "_osthread") == 0) {
                 _thread_osthread_offset = *(int*)(entry + offset_offset);
+            } else if (strcmp(field, "_anchor") == 0) {
+                _thread_anchor_offset = *(int*)(entry + offset_offset);
+            } else if (strcmp(field, "_thread_state") == 0) {
+                _thread_state_offset = *(int*)(entry + offset_offset);
             }
         } else if (strcmp(type, "OSThread") == 0) {
             if (strcmp(field, "_thread_id") == 0) {
                 _osthread_id_offset = *(int*)(entry + offset_offset);
             }
+        } else if (strcmp(type, "JavaFrameAnchor") == 0) {
+            if (strcmp(field, "_last_Java_sp") == 0) {
+                _anchor_sp_offset = *(int*)(entry + offset_offset);
+            } else if (strcmp(field, "_last_Java_pc") == 0) {
+                _anchor_pc_offset = *(int*)(entry + offset_offset);
+            }
+        } else if (strcmp(type, "CodeBlob") == 0) {
+            if (strcmp(field, "_frame_size") == 0) {
+                _frame_size_offset = *(int*)(entry + offset_offset);
+            }
+        } else if (strcmp(type, "Universe") == 0) {
+            if (strcmp(field, "_collectedHeap") == 0) {
+                _collected_heap_addr = **(char***)(entry + address_offset);
+            }
+        } else if (strcmp(type, "CollectedHeap") == 0) {
+            if (strcmp(field, "_is_gc_active") == 0) {
+                _is_gc_active_offset = *(int*)(entry + offset_offset);
+            }
         } else if (strcmp(type, "PermGen") == 0) {
             _has_perm_gen = true;
         }
@@ -93,12 +157,84 @@ void VMStructs::init(NativeCodeCache* libjvm) {
         entry += stride;
     }
 
+    _has_class_names = _klass_name_offset >= 0
+            && (_symbol_length_offset >= 0 || _symbol_length_and_refcount_offset >= 0)
+            && _symbol_body_offset >= 0
+            && _klass != NULL;
+}
+
+void VMStructs::initJvmFunctions() {
+    _get_stack_trace = (GetStackTraceFunc)_libjvm->findSymbol("_ZN8JvmtiEnv13GetStackTraceEP10JavaThreadiiP15_jvmtiFrameInfoPi");
+    if (_get_stack_trace == NULL) {
+        _get_stack_trace = (GetStackTraceFunc)_libjvm->findSymbol("_ZN8JvmtiEnv13GetStackTraceEP10JavaThreadiiP14jvmtiFrameInfoPi");
+    }
+
+    _unsafe_park = (UnsafeParkFunc)_libjvm->findSymbol("Unsafe_Park");
+    if (_unsafe_park == NULL) {
+        // In some macOS builds of JDK 11 Unsafe_Park appears to have a C++ decorated name
+        _unsafe_park = (UnsafeParkFunc)_libjvm->findSymbol("_ZL11Unsafe_ParkP7JNIEnv_P8_jobjecthl");
+    }
+
+    if (_frame_size_offset >= 0) {
+        _find_blob = (FindBlobFunc)_libjvm->findSymbol("_ZN9CodeCache16find_blob_unsafeEPv");
+        if (_find_blob == NULL) {
+            _find_blob = (FindBlobFunc)_libjvm->findSymbol("_ZN9CodeCache9find_blobEPv");
+        }
+    }
+
+    if (VM::hotspot_version() == 8 && _class_loader_data_offset >= 0 && _methods_offset >= 0 && _klass != NULL) {
+        _lock_func = (LockFunc)_libjvm->findSymbol("_ZN7Monitor28lock_without_safepoint_checkEv");
+        _unlock_func = (LockFunc)_libjvm->findSymbol("_ZN7Monitor6unlockEv");
+        _has_class_loader_data = _lock_func != NULL && _unlock_func != NULL;
+    }
+}
+
+void VMStructs::initThreadBridge(JNIEnv* env) {
     // Get eetop field - a bridge from Java Thread to VMThread
-    if (_thread_osthread_offset >= 0 && _osthread_id_offset >= 0) {
-        JNIEnv* env = VM::jni();
-        jclass threadClass = env->FindClass("java/lang/Thread");
-        if (threadClass != NULL) {
-            _eetop = env->GetFieldID(threadClass, "eetop", "J");
+    jthread thread;
+    if (VM::jvmti()->GetCurrentThread(&thread) != 0) {
+        return;
+    }
+
+    jclass thread_class = env->GetObjectClass(thread);
+    _eetop = env->GetFieldID(thread_class, "eetop", "J");
+    _tid = env->GetFieldID(thread_class, "tid", "J");
+    if (_eetop == NULL || _tid == NULL) {
+        return;
+    }
+
+    VMThread* vm_thread = VMThread::fromJavaThread(env, thread);
+    if (vm_thread == NULL) {
+        return;
+    }
+
+    // Workaround for JDK-8132510: it's not safe to call GetEnv() inside a signal handler
+    // since JDK 9, so we do it only for threads already registered in ThreadLocalStorage
+    for (int i = 0; i < 1024; i++) {
+        if (pthread_getspecific((pthread_key_t)i) == vm_thread) {
+            _tls_index = i;
+            break;
+        }
+    }
+
+    if (_tls_index < 0) {
+        return;
+    }
+
+    _env_offset = (intptr_t)env - (intptr_t)vm_thread;
+    _has_thread_bridge = true;
+}
+
+void VMStructs::initLogging(JNIEnv* env) {
+    // Workaround for JDK-8238460
+    if (VM::hotspot_version() >= 15) {
+        VMManagement* management = VM::management();
+        if (management != NULL) {
+            management->ExecuteDiagnosticCommand(env, env->NewStringUTF("VM.log what=jni+resolve=error"));
         }
     }
 }
+
+VMThread* VMThread::current() {
+    return (VMThread*)pthread_getspecific((pthread_key_t)_tls_index);
+}

src/vmStructs.h

@@ -24,15 +24,47 @@
 
 class VMStructs {
   protected:
+    static NativeCodeCache* _libjvm;
+
+    static bool _has_class_names;
+    static bool _has_class_loader_data;
+    static bool _has_thread_bridge;
+    static bool _has_perm_gen;
+
     static int _klass_name_offset;
     static int _symbol_length_offset;
     static int _symbol_length_and_refcount_offset;
     static int _symbol_body_offset;
-    static int _class_klass_offset;
+    static int _class_loader_data_offset;
+    static int _methods_offset;
     static int _thread_osthread_offset;
+    static int _thread_anchor_offset;
+    static int _thread_state_offset;
     static int _osthread_id_offset;
-    static bool _has_perm_gen;
+    static int _anchor_sp_offset;
+    static int _anchor_pc_offset;
+    static int _frame_size_offset;
+    static int _is_gc_active_offset;
+    static char* _collected_heap_addr;
+
     static jfieldID _eetop;
+    static jfieldID _tid;
+    static jfieldID _klass;
+    static int _tls_index;
+    static intptr_t _env_offset;
+
+    typedef void* (*FindBlobFunc)(const void*);
+    static FindBlobFunc _find_blob;
+
+    typedef void (*LockFunc)(void*);
+    static LockFunc _lock_func;
+    static LockFunc _unlock_func;
+
+    static uintptr_t readSymbol(const char* symbol_name);
+    static void initOffsets();
+    static void initJvmFunctions();
+    static void initThreadBridge(JNIEnv* env);
+    static void initLogging(JNIEnv* env);
 
     const char* at(int offset) {
         return (const char*)this + offset;
@@ -41,15 +73,47 @@ class VMStructs {
   public:
     static void init(NativeCodeCache* libjvm);
 
-    static bool available() {
-        return _klass_name_offset >= 0
-            && (_symbol_length_offset >= 0 || _symbol_length_and_refcount_offset >= 0)
-            && _symbol_body_offset >= 0
-            && _class_klass_offset >= 0;
+    static NativeCodeCache* libjvm() {
+        return _libjvm;
     }
 
-    static bool hasPermGen() {
-        return _has_perm_gen;
+    static bool hasClassNames() {
+        return _has_class_names;
+    }
+
+    static bool hasClassLoaderData() {
+        return _has_class_loader_data;
+    }
+
+    static bool hasThreadBridge() {
+        return _has_thread_bridge;
+    }
+
+    typedef jvmtiError (*GetStackTraceFunc)(void* self, void* thread,
+                                            jint start_depth, jint max_frame_count,
+                                            jvmtiFrameInfo* frame_buffer, jint* count_ptr);
+    static GetStackTraceFunc _get_stack_trace;
+
+    typedef void (JNICALL *UnsafeParkFunc)(JNIEnv*, jobject, jboolean, jlong);
+    static UnsafeParkFunc _unsafe_park;
+};
+
+
+class MethodList {
+  public:
+    enum { SIZE = 8 };
+
+  private:
+    intptr_t _method[SIZE];
+    int _ptr;
+    MethodList* _next;
+    int _padding;
+
+  public:
+    MethodList(MethodList* next) : _ptr(0), _next(next), _padding(0) {
+        for (int i = 0; i < SIZE; i++) {
+            _method[i] = 0x37;
+        }
     }
 };
 
@@ -60,8 +124,7 @@ class VMSymbol : VMStructs {
         if (_symbol_length_offset >= 0) {
           return *(unsigned short*) at(_symbol_length_offset);
         } else {
-          int length_and_refcount = *(unsigned int*) at(_symbol_length_and_refcount_offset);
-          return (length_and_refcount >> 16) & 0xffff;
+          return *(unsigned int*) at(_symbol_length_and_refcount_offset) >> 16;
         }
     }
 
@@ -70,8 +133,39 @@ class VMSymbol : VMStructs {
     }
 };
 
+class ClassLoaderData : VMStructs {
+  private:
+    void* mutex() {
+        return *(void**) at(sizeof(uintptr_t) * 3);
+    }
+
+  public:
+    void lock() {
+        _lock_func(mutex());
+    }
+
+    void unlock() {
+        _unlock_func(mutex());
+    }
+
+    MethodList** methodList() {
+        return (MethodList**) at(sizeof(uintptr_t) * 6 + 8);
+    }
+};
+
 class VMKlass : VMStructs {
   public:
+    static VMKlass* fromJavaClass(JNIEnv* env, jclass cls) {
+        if (_has_perm_gen) {
+            jobject klassOop = env->GetObjectField(cls, _klass);
+            return (VMKlass*)(*(uintptr_t**)klassOop + 2);
+        } else if (sizeof(VMKlass*) == 8) {
+            return (VMKlass*)(uintptr_t)env->GetLongField(cls, _klass);
+        } else {
+            return (VMKlass*)(uintptr_t)env->GetIntField(cls, _klass);
+        }
+    }
+
     static VMKlass* fromHandle(uintptr_t handle) {
         if (_has_perm_gen) {
             // On JDK 7 KlassHandle is a pointer to klassOop, hence one more indirection
@@ -84,29 +178,72 @@ class VMKlass : VMStructs {
     VMSymbol* name() {
         return *(VMSymbol**) at(_klass_name_offset);
     }
-};
 
-class java_lang_Class : VMStructs {
-  public:
-    VMKlass* klass() {
-        return *(VMKlass**) at(_class_klass_offset);
+    ClassLoaderData* classLoaderData() {
+        return *(ClassLoaderData**) at(_class_loader_data_offset);
+    }
+
+    int methodCount() {
+        int* methods = *(int**) at(_methods_offset);
+        return methods == NULL ? 0 : *methods & 0xffff;
     }
 };
 
 class VMThread : VMStructs {
   public:
-    static bool available() {
-        return _eetop != NULL;
-    }
+    static VMThread* current();
 
     static VMThread* fromJavaThread(JNIEnv* env, jthread thread) {
         return (VMThread*)(uintptr_t)env->GetLongField(thread, _eetop);
     }
 
+    static VMThread* fromEnv(JNIEnv* env) {
+        return (VMThread*)((intptr_t)env - _env_offset);
+    }
+
+    static jlong javaThreadId(JNIEnv* env, jthread thread) {
+        return env->GetLongField(thread, _tid);
+    }
+
+    static bool hasNativeId() {
+        return _thread_osthread_offset >= 0 && _osthread_id_offset >= 0;
+    }
+
     int osThreadId() {
         const char* osthread = *(const char**) at(_thread_osthread_offset);
         return *(int*)(osthread + _osthread_id_offset);
     }
+
+    int state() {
+        return _thread_state_offset >= 0 ? *(int*) at(_thread_state_offset) : 0;
+    }
+
+    uintptr_t& lastJavaSP() {
+        return *(uintptr_t*) (at(_thread_anchor_offset) + _anchor_sp_offset);
+    }
+
+    uintptr_t& lastJavaPC() {
+        return *(uintptr_t*) (at(_thread_anchor_offset) + _anchor_pc_offset);
+    }
+};
+
+class RuntimeStub : VMStructs {
+  public:
+    static RuntimeStub* findBlob(const void* pc) {
+        return _find_blob != NULL ? (RuntimeStub*)_find_blob(pc) : NULL;
+    }
+
+    int frameSize() {
+        return *(int*) at(_frame_size_offset);
+    }
+};
+
+class CollectedHeap : VMStructs {
+  public:
+    static bool isGCActive() {
+        return _collected_heap_addr != NULL && _is_gc_active_offset >= 0 &&
+               _collected_heap_addr[_is_gc_active_offset] != 0;
+    }
 };
 
 #endif // _VMSTRUCTS_H

src/wallClock.cpp

@@ -14,41 +14,73 @@
  * limitations under the License.
  */
 
-#include <poll.h>
-#include <string.h>
 #include <signal.h>
-#include <sys/types.h>
+#include <string.h>
+#include <time.h>
 #include <unistd.h>
+#include <sys/types.h>
 #include "wallClock.h"
-#include "os.h"
 #include "profiler.h"
 
 
+// Maximum number of threads sampled in one iteration. This limit serves as a throttle
+// when generating profiling signals. Otherwise applications with too many threads may
+// suffer from a big profiling overhead. Also, keeping this limit low enough helps
+// to avoid contention on a spin lock inside Profiler::recordSample().
 const int THREADS_PER_TICK = 8;
 
+// Set the hard limit for thread walking interval to 100 microseconds.
+// Smaller intervals are practically unusable due to large overhead.
+const long MIN_INTERVAL = 100000;
+
+// Stop profiling thread with this signal. The same signal is used inside JDK to interrupt I/O operations.
+const int WAKEUP_SIGNAL = SIGIO;
+
+
 long WallClock::_interval;
 bool WallClock::_sample_idle_threads;
 
 void WallClock::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {
-    Profiler::_instance.recordSample(ucontext, _interval, 0, NULL);
+    ExecutionEvent event;
+    event._thread_state = _sample_idle_threads ? Profiler::_instance.getThreadState(ucontext) : THREAD_RUNNING;
+    Profiler::_instance.recordSample(ucontext, _interval, 0, &event);
+}
+
+void WallClock::wakeupHandler(int signo) {
+    // Dummy handler for interrupting syscalls
+}
+
+long WallClock::adjustInterval(long interval, int thread_count) {
+    if (thread_count > THREADS_PER_TICK) {
+        interval /= (thread_count + THREADS_PER_TICK - 1) / THREADS_PER_TICK;
+    }
+    return interval;
+}
+
+void WallClock::sleep(long interval) {
+    struct timespec timeout;
+    timeout.tv_sec = interval / 1000000000;
+    timeout.tv_nsec = interval % 1000000000;
+
+    nanosleep(&timeout, NULL);
 }
 
 Error WallClock::start(Arguments& args) {
     if (args._interval < 0) {
         return Error("interval must be positive");
     }
-    _interval = args._interval ? args._interval : DEFAULT_INTERVAL;
-    _sample_idle_threads = strcmp(args._event, EVENT_WALL) == 0;
 
-    OS::installSignalHandler(SIGPROF, signalHandler);
+    _sample_idle_threads = strcmp(args._event_desc, EVENT_WALL) == 0;
 
-    if (pipe(_pipefd) != 0) {
-        return Error("Unable to create poll pipe");
-    }
+    // Increase default interval for wall clock mode due to larger number of sampled threads
+    _interval = args._interval ? args._interval : (_sample_idle_threads ? DEFAULT_INTERVAL * 5 : DEFAULT_INTERVAL);
+
+    OS::installSignalHandler(SIGVTALRM, signalHandler);
+    OS::installSignalHandler(WAKEUP_SIGNAL, NULL, wakeupHandler);
+
+    _running = true;
 
     if (pthread_create(&_thread, NULL, threadEntry, this) != 0) {
-        close(_pipefd[1]);
-        close(_pipefd[0]);
         return Error("Unable to create timer thread");
     }
 
@@ -56,39 +88,60 @@ Error WallClock::start(Arguments& args) {
 }
 
 void WallClock::stop() {
-    char val = 1;
-    ssize_t r = write(_pipefd[1], &val, sizeof(val));
-    (void)r;
-
-    close(_pipefd[1]);
+    _running = false;
+    pthread_kill(_thread, WAKEUP_SIGNAL);
     pthread_join(_thread, NULL);
-    close(_pipefd[0]);
 }
 
 void WallClock::timerLoop() {
-    ThreadList* thread_list = NULL;
-
     int self = OS::threadId();
+    ThreadFilter* thread_filter = Profiler::_instance.threadFilter();
+    bool thread_filter_enabled = thread_filter->enabled();
     bool sample_idle_threads = _sample_idle_threads;
-    struct pollfd fds = {_pipefd[0], POLLIN, 0};
-    int timeout = _interval > 1000000 ? (int)(_interval / 1000000) : 1;
 
-    while (poll(&fds, 1, timeout) == 0) {
-        if (thread_list == NULL) {
-            thread_list = OS::listThreads();
+    ThreadList* thread_list = OS::listThreads();
+    long long next_cycle_time = OS::nanotime();
+
+    while (_running) {
+        if (!_enabled) {
+            sleep(_interval);
+            continue;
+        }
+
+        if (sample_idle_threads) {
+            // Try to keep the wall clock interval stable, regardless of the number of profiled threads
+            int estimated_thread_count = thread_filter_enabled ? thread_filter->size() : thread_list->size();
+            next_cycle_time += adjustInterval(_interval, estimated_thread_count);
         }
 
         for (int count = 0; count < THREADS_PER_TICK; ) {
             int thread_id = thread_list->next();
             if (thread_id == -1) {
-                delete thread_list;
-                thread_list = NULL;
+                thread_list->rewind();
                 break;
             }
-            if (thread_id != self && (sample_idle_threads || OS::isThreadRunning(thread_id))) {
-                OS::sendSignalToThread(thread_id, SIGPROF);
-                count++;
+
+            if (thread_id == self || (thread_filter_enabled && !thread_filter->accept(thread_id))) {
+                continue;
             }
+
+            if (sample_idle_threads || OS::threadState(thread_id) == THREAD_RUNNING) {
+                if (OS::sendSignalToThread(thread_id, SIGVTALRM)) {
+                    count++;
+                }
+            }
+        }
+
+        if (sample_idle_threads) {
+            long long current_time = OS::nanotime();
+            if (next_cycle_time - current_time > MIN_INTERVAL) {
+                sleep(next_cycle_time - current_time);
+            } else {
+                next_cycle_time = current_time + MIN_INTERVAL;
+                sleep(MIN_INTERVAL);
+            }
+        } else {
+            sleep(_interval);
         }
     }
 

src/wallClock.h

@@ -28,7 +28,7 @@ class WallClock : public Engine {
     static long _interval;
     static bool _sample_idle_threads;
 
-    int _pipefd[2];
+    volatile bool _running;
     pthread_t _thread;
 
     void timerLoop();
@@ -39,6 +39,10 @@ class WallClock : public Engine {
     }
 
     static void signalHandler(int signo, siginfo_t* siginfo, void* ucontext);
+    static void wakeupHandler(int signo);
+
+    static long adjustInterval(long interval, int thread_count);
+    static void sleep(long interval);
 
   public:
     const char* name() {

test/LoadLibraryTest.java

@@ -1,7 +1,5 @@
-import java.net.InetAddress;
-import java.net.InetSocketAddress;
-import java.nio.ByteBuffer;
-import java.nio.channels.DatagramChannel;
+import java.lang.management.ClassLoadingMXBean;
+import java.lang.management.ManagementFactory;
 
 class LoadLibraryTest {
 
@@ -10,16 +8,14 @@ class LoadLibraryTest {
             Thread.sleep(10);
         }
 
-        // Late load of libnet.so and libnio.so
-        DatagramChannel ch = DatagramChannel.open();
-        ch.bind(new InetSocketAddress(0));
+        // Late load of libmanagement.so
+        ClassLoadingMXBean bean = ManagementFactory.getClassLoadingMXBean();
 
-        ByteBuffer buf = ByteBuffer.allocateDirect(1000);
-        InetSocketAddress target = new InetSocketAddress(InetAddress.getLoopbackAddress(), 1024);
-
-        while (true) {
-            ch.send(buf, target);
-            buf.clear();
+        long n = 0;
+        while (n >= 0) {
+            n += bean.getLoadedClassCount();
+            n += bean.getTotalLoadedClassCount();
+            n += bean.getUnloadedClassCount();
         }
     }
 }

test/load-library-test.sh

@@ -15,7 +15,7 @@ fi
      ${JAVA_HOME}/bin/javac LoadLibraryTest.java
   fi
 
-  ${JAVA_HOME}/bin/java LoadLibraryTest &
+  ${JAVA_HOME}/bin/java -agentpath:../build/libasyncProfiler.so LoadLibraryTest &
 
   FILENAME=/tmp/java.trace
   JAVAPID=$!
@@ -31,5 +31,5 @@ fi
     fi
   }
 
-  assert_string "Java_sun_nio"
+  assert_string "Java_sun_management"
 )

test/thread-smoke-test.sh

@@ -17,7 +17,7 @@ fi
 
   FILENAME=/tmp/java.trace
 
-  ${JAVA_HOME}/bin/java -agentpath:../build/libasyncProfiler.so=start,collapsed,threads,file=$FILENAME ThreadsTarget
+  ${JAVA_HOME}/bin/java -agentpath:../build/libasyncProfiler.so=start,event=cpu,collapsed,threads,file=$FILENAME ThreadsTarget
 
   # wait for normal termination