Release 1.8.8

(cherry picked from commit 3256d824de)

CHANGELOG.md

@@ -1,5 +1,33 @@
 # Changelog
 
+## [1.8.8] - 2022-09-10
+
+### Bug fixes
+ - Could not find NativeLibrary_load on JDK 11.0.15
+
+## [1.8.7] - 2021-10-01
+
+### Bug fixes
+ - Workaround for JDK-8173361
+ - Backported fix for "Accept timed out" exception
+
+## [1.8.6] - 2021-07-08
+
+### Improvements
+ - `log=none` option to suppress warnings about missing JVM symbols
+ - Sign macOS binaries
+
+### Bug fixes
+ - Workaround for JDK-8212160
+
+## [1.8.5] - 2021-03-22
+
+### Improvements
+ - Backported JFR to FlameGraph converter
+
+### Bug fixes
+ - Stricter `safemode` to avoid stack walking in suspicious cases
+
 ## [1.8.4] - 2021-02-24
 
 ### Improvements

Makefile

@@ -1,4 +1,4 @@
-PROFILER_VERSION=1.8.4
+PROFILER_VERSION=1.8.8
 JATTACH_VERSION=1.5
 JAVAC_RELEASE_VERSION=6
 
@@ -33,11 +33,13 @@ ifeq ($(OS), Darwin)
   CXXFLAGS += -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE
   INCLUDES += -I$(JAVA_HOME)/include/darwin
   SOEXT=dylib
+  CODESIGN=codesign -s "Developer ID" -o runtime --timestamp -v $(1)
   OS_TAG=macos
 else
   LIBS += -lrt
   INCLUDES += -I$(JAVA_HOME)/include/linux
   SOEXT=so
+  CODESIGN=
   ifeq ($(findstring musl,$(shell ldd /bin/ls)),musl)
     OS_TAG=linux-musl
   else
@@ -70,6 +72,8 @@ release: build $(PACKAGE_NAME).tar.gz
 $(PACKAGE_NAME).tar.gz: build/$(LIB_PROFILER) build/$(JATTACH) \
                         build/$(API_JAR) build/$(CONVERTER_JAR) \
                         profiler.sh LICENSE NOTICE *.md
+	$(call CODESIGN,build/$(LIB_PROFILER))
+	$(call CODESIGN,build/$(JATTACH))
 	mkdir -p $(PACKAGE_DIR)
 	cp -RP build profiler.sh LICENSE NOTICE *.md $(PACKAGE_DIR)
 	chmod -R 755 $(PACKAGE_DIR)

README.md

@@ -14,21 +14,16 @@ async-profiler can trace the following kinds of events:
 
 ## Download
 
-Latest release (1.8.4):
+Latest v1 release (1.8.8):
 
- - Linux x64 (glibc): [async-profiler-1.8.4-linux-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.4/async-profiler-1.8.4-linux-x64.tar.gz)
- - Linux x86 (glibc): [async-profiler-1.8.4-linux-x86.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.4/async-profiler-1.8.4-linux-x86.tar.gz)
- - Linux x64 (musl): [async-profiler-1.8.4-linux-musl-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.4/async-profiler-1.8.4-linux-musl-x64.tar.gz)
- - Linux ARM: [async-profiler-1.8.4-linux-arm.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.4/async-profiler-1.8.4-linux-arm.tar.gz)
- - Linux AArch64: [async-profiler-1.8.4-linux-aarch64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.4/async-profiler-1.8.4-linux-aarch64.tar.gz)
- - macOS x64: [async-profiler-1.8.4-macos-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.4/async-profiler-1.8.4-macos-x64.tar.gz)
+ - Linux x64 (glibc): [async-profiler-1.8.8-linux-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.8/async-profiler-1.8.8-linux-x64.tar.gz)
+ - Linux x86 (glibc): [async-profiler-1.8.8-linux-x86.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.8/async-profiler-1.8.8-linux-x86.tar.gz)
+ - Linux x64 (musl): [async-profiler-1.8.8-linux-musl-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.8/async-profiler-1.8.8-linux-musl-x64.tar.gz)
+ - Linux ARM: [async-profiler-1.8.8-linux-arm.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.8/async-profiler-1.8.8-linux-arm.tar.gz)
+ - Linux AArch64: [async-profiler-1.8.8-linux-aarch64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.8/async-profiler-1.8.8-linux-aarch64.tar.gz)
+ - macOS x64: [async-profiler-1.8.8-macos-x64.tar.gz](https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.8.8/async-profiler-1.8.8-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)
+[Other releases](https://github.com/jvm-profiling-tools/async-profiler/releases)
 
 Note: async-profiler also comes bundled with IntelliJ IDEA Ultimate 2018.3 and later.
 For more information refer to [IntelliJ IDEA documentation](https://www.jetbrains.com/help/idea/cpu-profiler.html).
@@ -241,7 +236,7 @@ $ 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/v1.8.4/src/arguments.cpp#L49).
+[in the source code](https://github.com/jvm-profiling-tools/async-profiler/blob/v1.8.8/src/arguments.cpp#L49).
 The `profiler.sh` script actually converts command line arguments to that format.
 
 For instance, `-e alloc` is converted to `event=alloc`, `-f profile.svg`

pom.xml

@@ -3,7 +3,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>tools.profiler</groupId>
     <artifactId>async-profiler</artifactId>
-    <version>1.8.4</version>
+    <version>1.8.8</version>
     <packaging>jar</packaging>
 
     <name>async-profiler</name>

src/arguments.cpp

@@ -201,6 +201,9 @@ Error Arguments::parse(const char* args) {
             CASE("threads")
                 _threads = true;
 
+            CASE("log")
+                _log = value == NULL || (strcmp(value, "none") != 0 && strcmp(value, "/dev/null") != 0);
+
             CASE("allkernel")
                 _ring = RING_KERNEL;
 

src/arguments.h

@@ -123,6 +123,7 @@ class Arguments {
     int _include;
     int _exclude;
     bool _threads;
+    bool _log;
     int _style;
     CStack _cstack;
     Output _output;
@@ -150,6 +151,7 @@ class Arguments {
         _include(0),
         _exclude(0),
         _threads(false),
+        _log(true),
         _style(0),
         _cstack(CSTACK_DEFAULT),
         _output(OUTPUT_NONE),

src/converter/FlameGraph.java

@@ -14,8 +14,10 @@
  * 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;
@@ -69,32 +71,36 @@ public class FlameGraph {
 
                 String[] trace = line.substring(0, space).split(";");
                 long ticks = Long.parseLong(line.substring(space + 1));
-
-                depth = Math.max(depth, trace.length);
-
-                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;
+                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 (PrintStream out = new PrintStream(output, "UTF-8")) {
+            try (BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(output), 32768);
+                 PrintStream out = new PrintStream(bos, false, "UTF-8")) {
                 dump(out);
             }
         }
@@ -137,7 +143,7 @@ public class FlameGraph {
     private void printFrame(PrintStream out, String title, Frame frame, int level, long x) {
         int type = frameType(title);
         title = stripSuffix(title);
-        if (title.indexOf('"') >= 0) {
+        if (title.indexOf('\'') >= 0) {
             title = title.replace("'", "\\'");
         }
 

src/converter/Main.java

@@ -25,6 +25,7 @@ public class Main {
         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 +1,89 @@
+/*
+ * 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.
+ */
+
+import one.jfr.ClassRef;
+import one.jfr.Frame;
+import one.jfr.JfrReader;
+import one.jfr.MethodRef;
+import one.jfr.StackTrace;
+
+import java.nio.charset.StandardCharsets;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Converts .jfr output produced by async-profiler to HTML Flame Graph.
+ */
+public class jfr2flame {
+
+    private static final int FRAME_KERNEL = 6;
+
+    private final JfrReader jfr;
+    private final Map<Long, String> methodNames = new HashMap<>();
+
+    public jfr2flame(JfrReader jfr) {
+        this.jfr = jfr;
+    }
+
+    public void convert(final FlameGraph fg) {
+        for (StackTrace stackTrace : jfr.stackTraces.values()) {
+            Frame[] frames = stackTrace.frames;
+            String[] trace = new String[frames.length];
+            for (int i = 0; i < frames.length; i++) {
+                trace[trace.length - 1 - i] = getMethodName(frames[i].method, frames[i].type);
+            }
+            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

@@ -19,6 +19,7 @@ import one.jfr.Frame;
 import one.jfr.JfrReader;
 import one.jfr.MethodRef;
 import one.jfr.Sample;
+import one.jfr.StackTrace;
 import one.proto.Proto;
 
 import java.io.File;
@@ -60,10 +61,10 @@ public class jfr2nflx {
         Proto nodes = new Proto(10000);
         Proto node = new Proto(10000);
 
-        for (Map.Entry<Integer, Frame[]> entry : jfr.stackTraces.entrySet()) {
+        for (Map.Entry<Integer, StackTrace> entry : jfr.stackTraces.entrySet()) {
             profile.field(5, nodes
                     .field(1, entry.getKey())
-                    .field(2, packNode(node, entry.getValue())));
+                    .field(2, packNode(node, entry.getValue().frames)));
             nodes.reset();
             node.reset();
         }

src/converter/one/jfr/JfrReader.java

@@ -51,7 +51,7 @@ public class JfrReader implements Closeable {
 
     public final long startNanos;
     public final long stopNanos;
-    public final Map<Integer, Frame[]> stackTraces = new HashMap<>();
+    public final Map<Integer, StackTrace> stackTraces = new HashMap<>();
     public final Map<Long, MethodRef> methods = new HashMap<>();
     public final Map<Long, ClassRef> classes = new HashMap<>();
     public final Map<Long, byte[]> symbols = new HashMap<>();
@@ -82,11 +82,7 @@ public class JfrReader implements Closeable {
             int size = buf.getInt();
             int type = buf.getInt();
             if (type == EVENT_EXECUTION_SAMPLE) {
-                long time = buf.getLong();
-                int tid = buf.getInt();
-                int stackTraceId = (int) buf.getLong();
-                short threadState = buf.getShort();
-                samples.add(new Sample(time, tid, stackTraceId, threadState));
+                readExecutionSample();
             } else {
                 buf.position(buf.position() + size - 8);
             }
@@ -95,6 +91,19 @@ public class JfrReader implements Closeable {
         Collections.sort(samples);
     }
 
+    private void readExecutionSample() {
+        long time = buf.getLong();
+        int tid = buf.getInt();
+        int stackTraceId = (int) buf.getLong();
+        short threadState = buf.getShort();
+        samples.add(new Sample(time, tid, stackTraceId, threadState));
+
+        StackTrace stackTrace = stackTraces.get(stackTraceId);
+        if (stackTrace != null) {
+            stackTrace.samples++;
+        }
+    }
+
     private void readCheckpoint(int checkpointOffset) {
         buf.position(checkpointOffset + 24);
 
@@ -135,7 +144,7 @@ public class JfrReader implements Closeable {
                 byte type = buf.get();
                 frames[j] = new Frame(method, type);
             }
-            stackTraces.put(id, frames);
+            stackTraces.put(id, new StackTrace(frames));
         }
     }
 

src/converter/one/jfr/StackTrace.java

@@ -0,0 +1,26 @@
+/*
+ * 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.
+ */
+
+package one.jfr;
+
+public class StackTrace {
+    public final Frame[] frames;
+    public long samples;
+
+    public StackTrace(Frame[] frames) {
+        this.frames = frames;
+    }
+}

src/engine.cpp

@@ -16,6 +16,7 @@
 
 #include "engine.h"
 #include "stackFrame.h"
+#include "vmStructs.h"
 
 
 Error Engine::check(Arguments& args) {
@@ -26,8 +27,7 @@ CStack Engine::cstack() {
     return CSTACK_FP;
 }
 
-int Engine::getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                           CodeCache* java_methods, CodeCache* runtime_stubs) {
+int Engine::getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth) {
     const void* pc;
     uintptr_t fp;
     uintptr_t prev_fp = (uintptr_t)&fp;
@@ -47,7 +47,7 @@ int Engine::getNativeTrace(void* ucontext, int tid, const void** callchain, int
 
     // Walk until the bottom of the stack or until the first Java frame
     while (depth < max_depth && pc >= valid_pc) {
-        if (java_methods->contains(pc) || runtime_stubs->contains(pc)) {
+        if (CodeHeap::contains(pc)) {
             break;
         }
 

src/engine.h

@@ -18,7 +18,6 @@
 #define _ENGINE_H
 
 #include "arguments.h"
-#include "codeCache.h"
 
 
 class Engine {
@@ -34,8 +33,7 @@ class Engine {
     virtual void onThreadEnd(int tid) {}
 
     virtual CStack cstack();
-    virtual int getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                               CodeCache* java_methods, CodeCache* runtime_stubs);
+    virtual int getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth);
 };
 
 #endif // _ENGINE_H

src/perfEvents.h

@@ -57,8 +57,7 @@ class PerfEvents : public Engine {
         destroyForThread(tid);
     }
 
-    int getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                       CodeCache* java_methods, CodeCache* runtime_stubs);
+    int getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth);
 
     static bool supported();
     static const char* getEventName(int event_id);

src/perfEvents_linux.cpp

@@ -37,6 +37,7 @@
 #include "spinLock.h"
 #include "stackFrame.h"
 #include "symbols.h"
+#include "vmStructs.h"
 
 
 // Ancient fcntl.h does not define F_SETOWN_EX constants and structures
@@ -535,9 +536,11 @@ Error PerfEvents::start(Arguments& args) {
 
     _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");
+        if (args._log) {
+            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;
@@ -576,8 +579,7 @@ void PerfEvents::stop() {
     }
 }
 
-int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                               CodeCache* java_methods, CodeCache* runtime_stubs) {
+int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth) {
     PerfEvent* event = &_events[tid];
     if (!event->tryLock()) {
         return 0;  // the event is being destroyed
@@ -601,7 +603,7 @@ int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain,
                     u64 ip = ring.next();
                     if (ip < PERF_CONTEXT_MAX) {
                         const void* iptr = (const void*)ip;
-                        if (java_methods->contains(iptr) || runtime_stubs->contains(iptr) || depth >= max_depth) {
+                        if (CodeHeap::contains(iptr) || depth >= max_depth) {
                             // Stop at the first Java frame
                             goto stack_complete;
                         }
@@ -614,7 +616,7 @@ int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain,
 
                     // 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) {
+                    if (CodeHeap::contains(pc) || depth >= max_depth) {
                         goto stack_complete;
                     }
                     callchain[depth++] = pc;
@@ -624,12 +626,12 @@ int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain,
                         const void* to = (const void*)ring.next();
                         ring.next();
 
-                        if (java_methods->contains(to) || runtime_stubs->contains(to) || depth >= max_depth) {
+                        if (CodeHeap::contains(to) || depth >= max_depth) {
                             goto stack_complete;
                         }
                         callchain[depth++] = to;
 
-                        if (java_methods->contains(from) || runtime_stubs->contains(from) || depth >= max_depth) {
+                        if (CodeHeap::contains(from) || depth >= max_depth) {
                             goto stack_complete;
                         }
                         callchain[depth++] = from;

src/perfEvents_macos.cpp

@@ -46,8 +46,7 @@ Error PerfEvents::start(Arguments& args) {
 void PerfEvents::stop() {
 }
 
-int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth,
-                               CodeCache* java_methods, CodeCache* runtime_stubs) {
+int PerfEvents::getNativeTrace(void* ucontext, int tid, const void** callchain, int max_depth) {
     return 0;
 }
 

src/profiler.cpp

@@ -166,6 +166,8 @@ void Profiler::addJavaMethod(const void* address, int length, jmethodID method)
     _jit_lock.lock();
     _java_methods.add(address, length, method, true);
     _jit_lock.unlock();
+
+    CodeHeap::updateBounds(address, (const char*)address + length);
 }
 
 void Profiler::removeJavaMethod(const void* address, jmethodID method) {
@@ -178,6 +180,8 @@ void Profiler::addRuntimeStub(const void* address, int length, const char* name)
     _stubs_lock.lock();
     _runtime_stubs.add(address, length, name, true);
     _stubs_lock.unlock();
+
+    CodeHeap::updateBounds(address, (const char*)address + length);
 }
 
 void Profiler::onThreadStart(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread) {
@@ -262,53 +266,26 @@ const char* Profiler::findNativeMethod(const void* address) {
     return lib == NULL ? NULL : lib->binarySearch(address);
 }
 
-// When thread is in Java state, it should have Java frame somewhere on the top of the stack
-bool Profiler::checkWalkable(void* ucontext) {
+// When a thread in Java state has a Java frame on the top of the stack,
+// it is known to be safe for stack walking
+bool Profiler::inJavaCode(void* ucontext) {
     if (ucontext == NULL) {
         return false;
     }
 
-    StackFrame frame(ucontext);
-    const void* pc = (const void*)frame.pc();
-    uintptr_t fp = frame.fp();
-    uintptr_t prev_fp = (uintptr_t)&fp;
-    uintptr_t bottom = prev_fp + 0x40000;
-
-    const void* const valid_pc = (const void*)0x1000;
-
-    // Walk until the bottom of the stack or until the first Java frame
-    for (int depth = 0; depth < 5 && pc >= valid_pc; depth++) {
-        if (_runtime_stubs.contains(pc)) {
-            _stubs_lock.lockShared();
-            jmethodID method = _runtime_stubs.find(pc);
-            _stubs_lock.unlockShared();
-            return method == NULL || strcmp((const char*)method, "call_stub") != 0;
-        } else if (_java_methods.contains(pc)) {
-            return true;
-        }
-
-        // Check if the next frame is below on the current stack
-        if (fp <= prev_fp || fp >= bottom) {
-            break;
-        }
-
-        // Frame pointer must be word aligned
-        if ((fp & (sizeof(uintptr_t) - 1)) != 0) {
-            break;
-        }
-
-        prev_fp = fp;
-        pc = ((const void**)fp)[1];
-        fp = ((uintptr_t*)fp)[0];
+    const void* pc = (const void*)StackFrame(ucontext).pc();
+    if (_runtime_stubs.contains(pc)) {
+        _stubs_lock.lockShared();
+        jmethodID method = _runtime_stubs.find(pc);
+        _stubs_lock.unlockShared();
+        return method == NULL || strcmp((const char*)method, "call_stub") != 0;
     }
-
-    return false;
+    return CodeHeap::contains(pc);
 }
 
 int Profiler::getNativeTrace(void* ucontext, ASGCT_CallFrame* frames, int tid) {
     const void* native_callchain[MAX_NATIVE_FRAMES];
-    int native_frames = _engine->getNativeTrace(ucontext, tid, native_callchain, MAX_NATIVE_FRAMES,
-                                                &_java_methods, &_runtime_stubs);
+    int native_frames = _engine->getNativeTrace(ucontext, tid, native_callchain, MAX_NATIVE_FRAMES);
 
     int depth = 0;
     jmethodID prev_method = NULL;
@@ -336,7 +313,7 @@ int Profiler::getJavaTraceAsync(void* ucontext, ASGCT_CallFrame* frames, int max
 
     if (_safe_mode & CHECK_STATE) {
         int state = vm_thread->state();
-        if ((state == 8 || state == 9) && !checkWalkable(ucontext)) {
+        if ((state == 8 || state == 9) && !inJavaCode(ucontext)) {
             // Thread is in Java state, but does not have a valid Java frame on top of the stack
             return 0;
         }
@@ -575,7 +552,7 @@ void Profiler::recordSample(void* ucontext, u64 counter, jint event_type, jmetho
 
         if (event_type == 0) {
             // Need to reset PerfEvents ring buffer, even though we discard the collected trace
-            _engine->getNativeTrace(ucontext, tid, NULL, 0, &_java_methods, &_runtime_stubs);
+            _engine->getNativeTrace(ucontext, tid, NULL, 0);
         }
         return;
     }
@@ -619,16 +596,16 @@ void Profiler::recordSample(void* ucontext, u64 counter, jint event_type, jmetho
     _locks[lock_index].unlock();
 }
 
-jboolean JNICALL Profiler::NativeLibraryLoadTrap(JNIEnv* env, jobject self, jstring name, jboolean builtin) {
-    jboolean result = ((jboolean JNICALL (*)(JNIEnv*, jobject, jstring, jboolean))
-                       _instance._original_NativeLibrary_load)(env, self, name, builtin);
+jboolean JNICALL Profiler::NativeLibraryLoadTrap(JNIEnv* env, jobject self, jstring name, jboolean builtin, jboolean throws) {
+    jboolean result = ((jboolean JNICALL (*)(JNIEnv*, jobject, jstring, jboolean, jboolean))
+                       _instance._original_NativeLibrary_load)(env, self, name, builtin, throws);
     _instance.updateSymbols(false);
     return result;
 }
 
-jboolean JNICALL Profiler::NativeLibrariesLoadTrap(JNIEnv* env, jobject self, jobject lib, jstring name, jboolean builtin, jboolean jni) {
-    jboolean result = ((jboolean JNICALL (*)(JNIEnv*, jobject, jobject, jstring, jboolean, jboolean))
-                       _instance._original_NativeLibrary_load)(env, self, lib, name, builtin, jni);
+jboolean JNICALL Profiler::NativeLibrariesLoadTrap(JNIEnv* env, jobject self, jobject lib, jstring name, jboolean builtin, jboolean jni, jboolean throws) {
+    jboolean result = ((jboolean JNICALL (*)(JNIEnv*, jobject, jobject, jstring, jboolean, jboolean, jboolean))
+                       _instance._original_NativeLibrary_load)(env, self, lib, name, builtin, jni, throws);
     _instance.updateSymbols(false);
     return result;
 }
@@ -639,6 +616,8 @@ void JNICALL Profiler::ThreadSetNativeNameTrap(JNIEnv* env, jobject self, jstrin
 }
 
 void Profiler::bindNativeLibraryLoad(JNIEnv* env, bool enable) {
+    static unsigned int warning_reported = 0;
+
     jclass NativeLibrary;
 
     if (_original_NativeLibrary_load == NULL) {
@@ -648,15 +627,25 @@ void Profiler::bindNativeLibraryLoad(JNIEnv* env, bool enable) {
             strcpy(original_jni_name, "Java_jdk_internal_loader_NativeLibraries_");
             _trapped_NativeLibrary_load = (void*)NativeLibrariesLoadTrap;
 
-            // JDK 15+
-            _load_method.name = (char*)"load";
-            _load_method.signature = (char*)"(Ljdk/internal/loader/NativeLibraries$NativeLibraryImpl;Ljava/lang/String;ZZ)Z";
+            if (env->GetStaticMethodID(NativeLibrary, "load", "(Ljdk/internal/loader/NativeLibraries$NativeLibraryImpl;Ljava/lang/String;ZZZ)Z") != NULL) {
+                // JDK 17+
+                _load_method.name = (char*)"load";
+                _load_method.signature = (char*)"(Ljdk/internal/loader/NativeLibraries$NativeLibraryImpl;Ljava/lang/String;ZZZ)Z";
+            } else {
+                // JDK 15-16
+                _load_method.name = (char*)"load";
+                _load_method.signature = (char*)"(Ljdk/internal/loader/NativeLibraries$NativeLibraryImpl;Ljava/lang/String;ZZ)Z";
+            }
 
         } else if ((NativeLibrary = env->FindClass("java/lang/ClassLoader$NativeLibrary")) != NULL) {
             strcpy(original_jni_name, "Java_java_lang_ClassLoader_00024NativeLibrary_");
             _trapped_NativeLibrary_load = (void*)NativeLibraryLoadTrap;
 
-            if (env->GetMethodID(NativeLibrary, "load0", "(Ljava/lang/String;Z)Z") != NULL) {
+            if (env->GetMethodID(NativeLibrary, "load0", "(Ljava/lang/String;ZZ)Z") != NULL) {
+                // JDK 11.0.15+ (workaround for JDK-8288547)
+                _load_method.name = (char*)"load0";
+                _load_method.signature = (char*)"(Ljava/lang/String;ZZ)Z";
+            } else if (env->GetMethodID(NativeLibrary, "load0", "(Ljava/lang/String;Z)Z") != NULL) {
                 // JDK 9-14
                 _load_method.name = (char*)"load0";
                 _load_method.signature = (char*)"(Ljava/lang/String;Z)Z";
@@ -671,13 +660,13 @@ void Profiler::bindNativeLibraryLoad(JNIEnv* env, bool enable) {
             }
 
         } else {
-            fprintf(stderr, "WARNING: Failed to intercept NativeLibraries.load()\n");
+            if (!warning_reported++) fprintf(stderr, "WARNING: async-profiler failed to intercept NativeLibraries.load()\n");
             return;
         }
 
         strcat(original_jni_name, _load_method.name);
         if ((_original_NativeLibrary_load = dlsym(VM::_libjava, original_jni_name)) == NULL) {
-            fprintf(stderr, "WARNING: Could not find %s\n", original_jni_name);
+            if (!warning_reported++) fprintf(stderr, "WARNING: async-profiler could not find %s\n", original_jni_name);
             return;
         }
 
@@ -686,7 +675,7 @@ void Profiler::bindNativeLibraryLoad(JNIEnv* env, bool enable) {
             ? "jdk/internal/loader/NativeLibraries"
             : "java/lang/ClassLoader$NativeLibrary";
         if ((NativeLibrary = env->FindClass(class_name)) == NULL) {
-            fprintf(stderr, "WARNING: Could not find %s\n", class_name);
+            if (!warning_reported++) fprintf(stderr, "WARNING: async-profiler could not find %s\n", class_name);
             return;
         }
     }
@@ -815,7 +804,7 @@ Engine* Profiler::selectEngine(const char* event_name) {
     }
 }
 
-Error Profiler::checkJvmCapabilities() {
+Error Profiler::checkJvmCapabilities(bool print_warnings) {
     if (VMStructs::libjvm() == NULL) {
         return Error("Could not find libjvm among loaded libraries. Unsupported JVM?");
     }
@@ -824,7 +813,7 @@ Error Profiler::checkJvmCapabilities() {
         return Error("Could not find VMThread bridge. Unsupported JVM?");
     }
 
-    if (VMStructs::_get_stack_trace == NULL) {
+    if (VMStructs::_get_stack_trace == NULL && print_warnings) {
         fprintf(stderr, "WARNING: Install JVM debug symbols to improve profile accuracy\n");
     }
 
@@ -837,7 +826,7 @@ Error Profiler::start(Arguments& args, bool reset) {
         return Error("Profiler already started");
     }
 
-    Error error = checkJvmCapabilities();
+    Error error = checkJvmCapabilities(args._log);
     if (error) {
         return error;
     }
@@ -894,7 +883,7 @@ Error Profiler::start(Arguments& args, bool reset) {
 
     updateSymbols(args._ring != RING_USER);
 
-    _safe_mode = args._safe_mode;
+    _safe_mode = VM::_safe_mode | args._safe_mode;
     if (VM::hotspot_version() < 8) {
         // Cannot use JVM TI stack walker during GC on non-HotSpot JVMs or with PermGen
         _safe_mode |= GC_TRACES | LAST_JAVA_PC;
@@ -960,7 +949,7 @@ Error Profiler::check(Arguments& args) {
         return Error("Profiler already started");
     }
 
-    Error error = checkJvmCapabilities();
+    Error error = checkJvmCapabilities(args._log);
     if (error) {
         return error;
     }

src/profiler.h

@@ -143,8 +143,8 @@ class Profiler {
     JNINativeMethod _load_method;
     void* _original_NativeLibrary_load;
     void* _trapped_NativeLibrary_load;
-    static jboolean JNICALL NativeLibraryLoadTrap(JNIEnv* env, jobject self, jstring name, jboolean builtin);
-    static jboolean JNICALL NativeLibrariesLoadTrap(JNIEnv* env, jobject self, jobject lib, jstring name, jboolean builtin, jboolean jni);
+    static jboolean JNICALL NativeLibraryLoadTrap(JNIEnv* env, jobject self, jstring name, jboolean builtin, jboolean throws);
+    static jboolean JNICALL NativeLibrariesLoadTrap(JNIEnv* env, jobject self, jobject lib, jstring name, jboolean builtin, jboolean jni, jboolean throws);
     void bindNativeLibraryLoad(JNIEnv* env, bool enable);
 
     // Support for intercepting Thread.setNativeName()
@@ -162,7 +162,7 @@ class Profiler {
     void onThreadEnd(jvmtiEnv* jvmti, JNIEnv* jni, jthread thread);
 
     const char* asgctError(int code);
-    bool checkWalkable(void* ucontext);
+    bool inJavaCode(void* ucontext);
     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);
@@ -180,7 +180,7 @@ class Profiler {
     void updateNativeThreadNames();
     bool excludeTrace(FrameName* fn, CallTraceSample* trace);
     Engine* selectEngine(const char* event_name);
-    Error checkJvmCapabilities();
+    Error checkJvmCapabilities(bool print_warnings);
 
   public:
     static Profiler _instance;

src/stackFrame_x64.cpp

@@ -122,7 +122,7 @@ bool StackFrame::checkInterruptedSyscall() {
     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) {
+        if ((int)arg2() == -1) {
             uintptr_t pc = this->pc();
             if ((pc & 0xfff) >= 7 && *(unsigned char*)(pc - 7) == 0xb8 && *(int*)(pc - 6) == SYS_poll) {
                 this->pc() = pc - 7;

src/vmEntry.cpp

@@ -33,6 +33,8 @@ static Arguments _agent_args;
 JavaVM* VM::_vm;
 jvmtiEnv* VM::_jvmti = NULL;
 int VM::_hotspot_version = 0;
+int VM::_hotspot_minor = 0;
+int VM::_safe_mode = 0;
 void* VM::_libjvm;
 void* VM::_libjava;
 AsyncGetCallTrace VM::_asyncGetCallTrace;
@@ -64,6 +66,11 @@ void VM::init(JavaVM* vm, bool attach) {
                 _hotspot_version = 6;
             } else if ((_hotspot_version = atoi(prop)) < 9) {
                 _hotspot_version = 9;
+            } else {
+                const char* p = strchr(prop, '.');
+                if (p != NULL && (p = strchr(p + 1, '.')) != NULL) {
+                    _hotspot_minor = atoi(p + 1);
+                }
             }
             _jvmti->Deallocate((unsigned char*)prop);
         }
@@ -109,12 +116,16 @@ void VM::init(JavaVM* vm, bool attach) {
     _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_DEATH, NULL);
     _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_LOAD, NULL);
     _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_PREPARE, NULL);
-    _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_COMPILED_METHOD_LOAD, NULL);
-    _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_COMPILED_METHOD_UNLOAD, NULL);
+    if ((_safe_mode & 14) != 14) {  // POP_FRAME + SCAN_STACK + LAST_JAVA_PC
+        // Workaround for JDK-8173361: avoid CompiledMethodLoad events when they are not needed  
+        _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_COMPILED_METHOD_LOAD, NULL);
+        _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_COMPILED_METHOD_UNLOAD, NULL);
+    }
     _jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_DYNAMIC_CODE_GENERATED, NULL);
 
     if (attach) {
         loadAllMethodIDs(jvmti(), jni());
+        DisableSweeper ds;
         _jvmti->GenerateEvents(JVMTI_EVENT_DYNAMIC_CODE_GENERATED);
         _jvmti->GenerateEvents(JVMTI_EVENT_COMPILED_METHOD_LOAD);
     }
@@ -263,7 +274,24 @@ Agent_OnAttach(JavaVM* vm, char* options, void* reserved) {
 
 extern "C" JNIEXPORT jint JNICALL
 JNI_OnLoad(JavaVM* vm, void* reserved) {
+    JNIEnv* jni;
+    if (vm->GetEnv((void**)&jni, JNI_VERSION_1_6) != 0) {
+        return 0;
+    }
+
+    jclass cls = jni->FindClass("java/lang/System");
+    jmethodID getProperty = jni->GetStaticMethodID(cls, "getProperty", "(Ljava/lang/String;)Ljava/lang/String;");
+    jstring prop = (jstring)jni->CallStaticObjectMethod(cls, getProperty, jni->NewStringUTF("AsyncProfiler.safemode"));
+
+    const char* chars;
+    if (prop != NULL && (chars = jni->GetStringUTFChars(prop, NULL)) != NULL) {
+        VM::_safe_mode = strtol(chars, NULL, 0);
+        jni->ReleaseStringUTFChars(prop, chars);
+    } else {
+        jni->ExceptionClear();
+    }
+
     VM::init(vm, true);
-    JavaAPI::registerNatives(VM::jvmti(), VM::jni());
+    JavaAPI::registerNatives(VM::jvmti(), jni);
     return JNI_VERSION_1_6;
 }

src/vmEntry.h

@@ -90,6 +90,7 @@ class VM {
     static jvmtiError (JNICALL *_orig_RetransformClasses)(jvmtiEnv*, jint, const jclass* classes);
     static volatile int _in_redefine_classes;
     static int _hotspot_version;
+    static int _hotspot_minor;
 
     static void ready();
     static void* getLibraryHandle(const char* name);
@@ -97,6 +98,7 @@ class VM {
     static void loadAllMethodIDs(jvmtiEnv* jvmti, JNIEnv* jni);
 
   public:
+    static int _safe_mode;
     static void* _libjvm;
     static void* _libjava;
     static AsyncGetCallTrace _asyncGetCallTrace;
@@ -120,6 +122,10 @@ class VM {
         return _hotspot_version;
     }
 
+    static int hotspot_minor() {
+        return _hotspot_minor;
+    }
+
     static bool inRedefineClasses() {
         return _in_redefine_classes > 0;
     }

src/vmStructs.cpp

@@ -17,6 +17,7 @@
 #include <pthread.h>
 #include <stdint.h>
 #include <string.h>
+#include <unistd.h>
 #include "vmStructs.h"
 #include "vmEntry.h"
 
@@ -43,6 +44,8 @@ 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;
+const void* VMStructs::_code_heap_low = NO_MIN_ADDRESS;
+const void* VMStructs::_code_heap_high = NO_MAX_ADDRESS;
 
 jfieldID VMStructs::_eetop;
 jfieldID VMStructs::_tid;
@@ -55,6 +58,8 @@ VMStructs::UnsafeParkFunc VMStructs::_unsafe_park = NULL;
 VMStructs::FindBlobFunc VMStructs::_find_blob = NULL;
 VMStructs::LockFunc VMStructs::_lock_func;
 VMStructs::LockFunc VMStructs::_unlock_func;
+char* VMStructs::_method_flushing = NULL;
+int* VMStructs::_sweep_started = NULL;
 
 
 uintptr_t VMStructs::readSymbol(const char* symbol_name) {
@@ -90,6 +95,11 @@ void VMStructs::initOffsets() {
         return;
     }
 
+    char* code_heap_addr = NULL;
+    int code_heap_memory_offset = -1;
+    int vs_low_offset = -1;
+    int vs_high_offset = -1;
+
     while (true) {
         const char* type = *(const char**)(entry + type_offset);
         const char* field = *(const char**)(entry + field_offset);
@@ -142,6 +152,24 @@ void VMStructs::initOffsets() {
             if (strcmp(field, "_frame_size") == 0) {
                 _frame_size_offset = *(int*)(entry + offset_offset);
             }
+        } else if (strcmp(type, "CodeCache") == 0) {
+            if (strcmp(field, "_heap") == 0) {
+                code_heap_addr = **(char***)(entry + address_offset);
+            } else if (strcmp(field, "_high_bound") == 0) {
+                _code_heap_high = **(const void***)(entry + address_offset);
+            } else if (strcmp(field, "_low_bound") == 0) {
+                _code_heap_low = **(const void***)(entry + address_offset);
+            }
+        } else if (strcmp(type, "CodeHeap") == 0) {
+            if (strcmp(field, "_memory") == 0) {
+                code_heap_memory_offset = *(int*)(entry + offset_offset);
+            }
+        } else if (strcmp(type, "VirtualSpace") == 0) {
+            if (strcmp(field, "_low_boundary") == 0) {
+                vs_low_offset = *(int*)(entry + offset_offset);
+            } else if (strcmp(field, "_high_boundary") == 0) {
+                vs_high_offset = *(int*)(entry + offset_offset);
+            }
         } else if (strcmp(type, "Universe") == 0) {
             if (strcmp(field, "_collectedHeap") == 0) {
                 _collected_heap_addr = **(char***)(entry + address_offset);
@@ -161,6 +189,11 @@ void VMStructs::initOffsets() {
             && (_symbol_length_offset >= 0 || _symbol_length_and_refcount_offset >= 0)
             && _symbol_body_offset >= 0
             && _klass != NULL;
+
+    if (code_heap_addr != NULL && code_heap_memory_offset >= 0 && vs_low_offset >= 0 && vs_high_offset >= 0) {
+        _code_heap_low = *(const void**)(code_heap_addr + code_heap_memory_offset + vs_low_offset);
+        _code_heap_high = *(const void**)(code_heap_addr + code_heap_memory_offset + vs_high_offset);
+    }
 }
 
 void VMStructs::initJvmFunctions() {
@@ -187,6 +220,12 @@ void VMStructs::initJvmFunctions() {
         _unlock_func = (LockFunc)_libjvm->findSymbol("_ZN7Monitor6unlockEv");
         _has_class_loader_data = _lock_func != NULL && _unlock_func != NULL;
     }
+
+    if ((VM::hotspot_version() > 0 && VM::hotspot_version() < 11) ||
+        (VM::hotspot_version() == 11 && VM::hotspot_minor() < 10)) {
+        _method_flushing = (char*)_libjvm->findSymbol("MethodFlushing");
+        _sweep_started = (int*)_libjvm->findSymbol("_ZN14NMethodSweeper14_sweep_startedE");
+    }
 }
 
 void VMStructs::initThreadBridge(JNIEnv* env) {
@@ -238,3 +277,27 @@ void VMStructs::initLogging(JNIEnv* env) {
 VMThread* VMThread::current() {
     return (VMThread*)pthread_getspecific((pthread_key_t)_tls_index);
 }
+
+DisableSweeper::DisableSweeper() {
+    // Workaround for JDK-8212160: Temporarily disable MethodFlushing
+    // while generating initial set of CompiledMethodLoad events
+    _enabled = _method_flushing != NULL && *_method_flushing;
+    if (!_enabled) return;
+
+    *_method_flushing = 0;
+    __sync_synchronize();
+
+    // Wait a bit in case sweeping has already started
+    for (int i = 0; i < 4; i++) {
+        if (_sweep_started == NULL || *_sweep_started) {
+            usleep(1000);
+        }
+    }
+}
+
+DisableSweeper::~DisableSweeper() {
+    if (!_enabled) return;
+
+    *_method_flushing = 1;
+    __sync_synchronize();
+}

src/vmStructs.h

@@ -46,6 +46,8 @@ class VMStructs {
     static int _frame_size_offset;
     static int _is_gc_active_offset;
     static char* _collected_heap_addr;
+    static const void* _code_heap_low;
+    static const void* _code_heap_high;
 
     static jfieldID _eetop;
     static jfieldID _tid;
@@ -60,6 +62,9 @@ class VMStructs {
     static LockFunc _lock_func;
     static LockFunc _unlock_func;
 
+    static char* _method_flushing;
+    static int* _sweep_started;
+
     static uintptr_t readSymbol(const char* symbol_name);
     static void initOffsets();
     static void initJvmFunctions();
@@ -238,6 +243,18 @@ class RuntimeStub : VMStructs {
     }
 };
 
+class CodeHeap : VMStructs {
+  public:
+    static bool contains(const void* pc) {
+        return _code_heap_low <= pc && pc < _code_heap_high;
+    }
+
+    static void updateBounds(const void* start, const void* end) {
+        if (start < _code_heap_low) _code_heap_low = start;
+        if (end > _code_heap_high) _code_heap_high = end;
+    }
+};
+
 class CollectedHeap : VMStructs {
   public:
     static bool isGCActive() {
@@ -246,4 +263,13 @@ class CollectedHeap : VMStructs {
     }
 };
 
+class DisableSweeper : VMStructs {
+  private:
+    bool _enabled;
+
+  public:
+    DisableSweeper();
+    ~DisableSweeper();
+};
+
 #endif // _VMSTRUCTS_H