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profiler.cpp
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/*
* Copyright 2016 Andrei Pangin
* Copyright 2024 Datadog, Inc
*
* 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 "profiler.h"
#include "asyncSampleMutex.h"
#include "context.h"
#include "counters.h"
#include "ctimer.h"
#include "dwarf.h"
#include "flightRecorder.h"
#include "itimer.h"
#include "j9Ext.h"
#include "j9WallClock.h"
#include "objectSampler.h"
#include "os.h"
#include "perfEvents.h"
#include "safeAccess.h"
#include "stackFrame.h"
#include "stackWalker.h"
#include "symbols.h"
#include "thread.h"
#include "vmStructs.h"
#include "wallClock.h"
#include <algorithm>
#include <dlfcn.h>
#include <fstream>
#include <memory>
#include <set>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <unistd.h>
// The instance is not deleted on purpose, since profiler structures
// can be still accessed concurrently during VM termination
Profiler *const Profiler::_instance = new Profiler();
static void (*orig_trapHandler)(int signo, siginfo_t *siginfo, void *ucontext);
static void (*orig_segvHandler)(int signo, siginfo_t *siginfo, void *ucontext);
static void (*orig_busHandler)(int signo, siginfo_t *siginfo, void *ucontext);
static Engine noop_engine;
static PerfEvents perf_events;
static WallClockASGCT wall_asgct_engine;
static WallClockJVMTI wall_jvmti_engine;
static J9WallClock j9_engine;
static ITimer itimer;
static CTimer ctimer;
// Stack recovery techniques used to workaround AsyncGetCallTrace flaws.
// Can be disabled with 'safemode' option.
enum StackRecovery {
UNKNOWN_JAVA = (1 << 0),
POP_STUB = (1 << 1),
POP_METHOD = (1 << 2),
UNWIND_NATIVE = (1 << 3),
LAST_JAVA_PC = (1 << 4),
GC_TRACES = (1 << 5),
};
static inline int makeFrame(ASGCT_CallFrame *frames, jint type, jmethodID id) {
frames[0].bci = type;
frames[0].method_id = id;
return 1;
}
static inline int makeFrame(ASGCT_CallFrame *frames, jint type, uintptr_t id) {
return makeFrame(frames, type, (jmethodID)id);
}
static inline int makeFrame(ASGCT_CallFrame *frames, jint type,
const char *id) {
return makeFrame(frames, type, (jmethodID)id);
}
void Profiler::addJavaMethod(const void *address, int length,
jmethodID method) {
CodeHeap::updateBounds(address, (const char *)address + length);
}
void Profiler::addRuntimeStub(const void *address, int length,
const char *name) {
_stubs_lock.lock();
_runtime_stubs.add(address, length, name, true);
_stubs_lock.unlock();
if (strcmp(name, "call_stub") == 0) {
_call_stub_begin = address;
_call_stub_end = (const char *)address + length;
}
CodeHeap::updateBounds(address, (const char *)address + length);
}
void Profiler::onThreadStart(jvmtiEnv *jvmti, JNIEnv *jni, jthread thread) {
ProfiledThread::initCurrentThread();
int tid = ProfiledThread::currentTid();
if (_thread_filter.enabled()) {
_thread_filter.remove(tid);
}
updateThreadName(jvmti, jni, thread, true);
_cpu_engine->registerThread(tid);
_wall_engine->registerThread(tid);
}
void Profiler::onThreadEnd(jvmtiEnv *jvmti, JNIEnv *jni, jthread thread) {
int tid = ProfiledThread::currentTid();
if (_thread_filter.enabled()) {
_thread_filter.remove(tid);
}
updateThreadName(jvmti, jni, thread, true);
_cpu_engine->unregisterThread(tid);
// unregister here because JNI callers generally don't know about thread exits
_wall_engine->unregisterThread(tid);
ProfiledThread::release();
}
int Profiler::registerThread(int tid) {
return _instance->_cpu_engine->registerThread(tid) |
_instance->_wall_engine->registerThread(tid);
}
void Profiler::unregisterThread(int tid) {
_instance->_cpu_engine->unregisterThread(tid);
_instance->_wall_engine->unregisterThread(tid);
}
const char *Profiler::asgctError(int code) {
switch (code) {
case ticks_no_Java_frame:
case ticks_unknown_not_Java:
// Not in Java context at all; this is not an error
return NULL;
case ticks_thread_exit:
// The last Java frame has been popped off, only native frames left
return NULL;
case ticks_GC_active:
return "GC_active";
case ticks_unknown_Java:
return "unknown_Java";
case ticks_not_walkable_Java:
return "not_walkable_Java";
case ticks_not_walkable_not_Java:
return "not_walkable_not_Java";
case ticks_deopt:
return "deoptimization";
case ticks_safepoint:
return "safepoint";
case ticks_skipped:
return "skipped";
case ticks_unknown_state:
// Zing sometimes returns it
return "unknown_state";
default:
// Should not happen
return "unexpected_state";
}
}
inline u32 Profiler::getLockIndex(int tid) {
u32 lock_index = tid;
lock_index ^= lock_index >> 8;
lock_index ^= lock_index >> 4;
return lock_index % CONCURRENCY_LEVEL;
}
void Profiler::updateSymbols(bool kernel_symbols) {
Symbols::parseLibraries(&_native_libs, kernel_symbols);
}
void Profiler::mangle(const char *name, char *buf, size_t size) {
char *buf_end = buf + size;
strcpy(buf, "_ZN");
buf += 3;
const char *c;
while ((c = strstr(name, "::")) != NULL && buf + (c - name) + 4 < buf_end) {
int n = snprintf(buf, buf_end - buf, "%d", (int)(c - name));
if (n < 0 || n >= buf_end - buf) {
if (n < 0) {
Log::debug("Error in snprintf.");
}
goto end;
}
buf += n;
memcpy(buf, name, c - name);
buf += c - name;
name = c + 2;
}
if (buf < buf_end) {
snprintf(buf, buf_end - buf, "%d%sE*", (int)strlen(name), name);
}
end:
buf_end[-1] = '\0';
}
const void *Profiler::resolveSymbol(const char *name) {
char mangled_name[256];
if (strstr(name, "::") != NULL) {
mangle(name, mangled_name, sizeof(mangled_name));
name = mangled_name;
}
size_t len = strlen(name);
int native_lib_count = _native_libs.count();
if (len > 0 && name[len - 1] == '*') {
for (int i = 0; i < native_lib_count; i++) {
const void *address = _native_libs[i]->findSymbolByPrefix(name, len - 1);
if (address != NULL) {
return address;
}
}
} else {
for (int i = 0; i < native_lib_count; i++) {
const void *address = _native_libs[i]->findSymbol(name);
if (address != NULL) {
return address;
}
}
}
return NULL;
}
// For BCI_NATIVE_FRAME, library index is encoded ahead of the symbol name
const char *Profiler::getLibraryName(const char *native_symbol) {
short lib_index = NativeFunc::libIndex(native_symbol);
if (lib_index >= 0 && lib_index < _native_libs.count()) {
const char *s = _native_libs[lib_index]->name();
if (s != NULL) {
const char *p = strrchr(s, '/');
return p != NULL ? p + 1 : s;
}
}
return NULL;
}
CodeCache *Profiler::findJvmLibrary(const char *lib_name) {
return VM::isOpenJ9() ? findLibraryByName(lib_name) : VMStructs::libjvm();
}
CodeCache *Profiler::findLibraryByName(const char *lib_name) {
const size_t lib_name_len = strlen(lib_name);
const int native_lib_count = _native_libs.count();
for (int i = 0; i < native_lib_count; i++) {
const char *s = _native_libs[i]->name();
if (s != NULL) {
const char *p = strrchr(s, '/');
if (p != NULL && strncmp(p + 1, lib_name, lib_name_len) == 0) {
return _native_libs[i];
}
}
}
return NULL;
}
CodeCache *Profiler::findLibraryByAddress(const void *address) {
const int native_lib_count = _native_libs.count();
for (int i = 0; i < native_lib_count; i++) {
if (_native_libs[i]->contains(address)) {
return _native_libs[i];
}
}
return NULL;
}
const char *Profiler::findNativeMethod(const void *address) {
CodeCache *lib = findLibraryByAddress(address);
return lib == NULL ? NULL : lib->binarySearch(address);
}
CodeBlob *Profiler::findRuntimeStub(const void *address) {
return _runtime_stubs.findBlobByAddress(address);
}
bool Profiler::isAddressInCode(const void *pc) {
if (CodeHeap::contains(pc)) {
return CodeHeap::findNMethod(pc) != NULL &&
!(pc >= _call_stub_begin && pc < _call_stub_end);
} else {
return findLibraryByAddress(pc) != NULL;
}
}
int Profiler::getNativeTrace(void *ucontext, ASGCT_CallFrame *frames,
int event_type, int tid, StackContext *java_ctx,
bool *truncated) {
if (_cstack == CSTACK_NO ||
(event_type == BCI_ALLOC || event_type == BCI_ALLOC_OUTSIDE_TLAB) ||
(event_type != BCI_CPU && event_type != BCI_WALL &&
_cstack == CSTACK_DEFAULT)) {
return 0;
}
const void *callchain[MAX_NATIVE_FRAMES];
int native_frames = 0;
if (event_type == BCI_CPU && _cpu_engine == &perf_events) {
native_frames +=
PerfEvents::walkKernel(tid, callchain + native_frames,
MAX_NATIVE_FRAMES - native_frames, java_ctx);
}
if (_cstack == CSTACK_VM) {
return 0;
} else if (_cstack == CSTACK_DWARF) {
native_frames += StackWalker::walkDwarf(ucontext, callchain + native_frames,
MAX_NATIVE_FRAMES - native_frames,
java_ctx, truncated);
} else {
native_frames += StackWalker::walkFP(ucontext, callchain + native_frames,
MAX_NATIVE_FRAMES - native_frames,
java_ctx, truncated);
}
return convertNativeTrace(native_frames, callchain, frames);
}
int Profiler::convertNativeTrace(int native_frames, const void **callchain,
ASGCT_CallFrame *frames) {
int depth = 0;
jmethodID prev_method = NULL;
for (int i = 0; i < native_frames; i++) {
const char *current_method_name = findNativeMethod(callchain[i]);
if (current_method_name != NULL &&
NativeFunc::isMarked(current_method_name)) {
// This is C++ interpreter frame, this and later frames should be reported
// as Java frames returned by AGCT. Terminate the scan here.
return depth;
}
jmethodID current_method = (jmethodID)current_method_name;
if (current_method == prev_method && _cstack == CSTACK_LBR) {
// Skip duplicates in LBR stack, where branch_stack[N].from ==
// branch_stack[N+1].to
prev_method = NULL;
} else {
frames[depth].bci = BCI_NATIVE_FRAME;
frames[depth].method_id = prev_method = current_method;
depth++;
}
}
return depth;
}
int Profiler::getJavaTraceAsync(void *ucontext, ASGCT_CallFrame *frames,
int max_depth, StackContext *java_ctx,
bool *truncated) {
// 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
VMThread *vm_thread = VMThread::current();
if (vm_thread == NULL) {
Counters::increment(AGCT_NOT_REGISTERED_IN_TLS);
return 0;
}
JNIEnv *jni = VM::jni();
if (jni == NULL) {
// Not a Java thread
Counters::increment(AGCT_NOT_JAVA);
return 0;
}
StackFrame frame(ucontext);
uintptr_t saved_pc, saved_sp, saved_fp;
if (ucontext != NULL) {
saved_pc = frame.pc();
saved_sp = frame.sp();
saved_fp = frame.fp();
if (saved_pc >= (uintptr_t)_call_stub_begin &&
saved_pc < (uintptr_t)_call_stub_end) {
// call_stub is unsafe to walk
frames->bci = BCI_ERROR;
frames->method_id = (jmethodID) "call_stub";
return 1;
}
if (!VMStructs::isSafeToWalk(saved_pc)) {
frames->bci = BCI_NATIVE_FRAME;
CodeBlob *codeBlob =
VMStructs::libjvm()->findBlobByAddress((const void *)saved_pc);
if (codeBlob) {
frames->method_id = (jmethodID)codeBlob->_name;
} else {
frames->method_id = (jmethodID) "unknown_unwalkable";
}
return 1;
}
} else {
return 0;
}
int state = vm_thread->state();
// from OpenJDK
// https://github.com/openjdk/jdk/blob/7455bb23c1d18224e48e91aae4f11fe114d04fab/src/hotspot/share/utilities/globalDefinitions.hpp#L1030
/*
enum JavaThreadState {
_thread_uninitialized = 0, // should never happen (missing
initialization) _thread_new = 2, // just starting up, i.e., in
process of being initialized _thread_new_trans = 3, // corresponding
transition state (not used, included for completeness) _thread_in_native = 4,
// running in native code _thread_in_native_trans = 5, // corresponding
transition state _thread_in_vm = 6, // running in VM
_thread_in_vm_trans = 7, // corresponding transition state
_thread_in_Java = 8, // running in Java or in stub code
_thread_in_Java_trans = 9, // corresponding transition state (not
used, included for completeness) _thread_blocked = 10, // blocked in
vm _thread_blocked_trans = 11, // corresponding transition state
_thread_max_state = 12 // maximum thread state+1 - used for
statistics allocation
};
*/
bool in_java = (state == 8 || state == 9);
if (in_java && java_ctx->sp != 0) {
// skip ahead to the Java frames before calling AGCT
frame.restore((uintptr_t)java_ctx->pc, java_ctx->sp, java_ctx->fp);
} else if (state != 0 && vm_thread->lastJavaSP() == 0) {
// we haven't found the top Java frame ourselves, and the lastJavaSP wasn't
// recorded either when not in the Java state, lastJava ucontext will be
// used by AGCT
Counters::increment(AGCT_NATIVE_NO_JAVA_CONTEXT);
return 0;
}
bool blocked_in_vm = (state == 10 || state == 11);
// avoid unwinding during deoptimization
if (blocked_in_vm && vm_thread->osThreadState() == ThreadState::RUNNABLE) {
Counters::increment(AGCT_BLOCKED_IN_VM);
return 0;
}
JitWriteProtection jit(false);
ASGCT_CallTrace trace = {jni, 0, frames};
VM::_asyncGetCallTrace(&trace, max_depth, ucontext);
if (trace.num_frames > 0) {
frame.restore(saved_pc, saved_sp, saved_fp);
return trace.num_frames;
}
if ((trace.num_frames == ticks_unknown_Java ||
trace.num_frames == ticks_not_walkable_Java) &&
!(_safe_mode & UNKNOWN_JAVA) && ucontext != NULL) {
CodeBlob *stub = NULL;
_stubs_lock.lockShared();
if (_runtime_stubs.contains((const void *)frame.pc())) {
stub = findRuntimeStub((const void *)frame.pc());
}
_stubs_lock.unlockShared();
if (stub != NULL) {
if (_cstack != CSTACK_NO) {
max_depth -= makeFrame(trace.frames++, BCI_NATIVE_FRAME, stub->_name);
}
if (!(_safe_mode & POP_STUB) &&
frame.unwindStub((instruction_t *)stub->_start, stub->_name) &&
isAddressInCode((const void *)frame.pc())) {
VM::_asyncGetCallTrace(&trace, max_depth, ucontext);
}
} else if (VMStructs::hasMethodStructs()) {
NMethod *nmethod = CodeHeap::findNMethod((const void *)frame.pc());
if (nmethod != NULL && nmethod->isNMethod() && nmethod->isAlive()) {
VMMethod *method = nmethod->method();
if (method != NULL) {
jmethodID method_id = method->id();
if (method_id != NULL) {
max_depth -= makeFrame(trace.frames++, 0, method_id);
}
if (!(_safe_mode & POP_METHOD) && frame.unwindCompiled(nmethod) &&
isAddressInCode((const void *)frame.pc())) {
VM::_asyncGetCallTrace(&trace, max_depth, ucontext);
}
}
} else if (nmethod != NULL) {
if (_cstack != CSTACK_NO) {
max_depth -=
makeFrame(trace.frames++, BCI_NATIVE_FRAME, nmethod->name());
}
if (!(_safe_mode & POP_STUB) &&
frame.unwindStub(NULL, nmethod->name()) &&
isAddressInCode((const void *)frame.pc())) {
VM::_asyncGetCallTrace(&trace, max_depth, ucontext);
}
}
}
} else if (trace.num_frames == ticks_unknown_not_Java &&
!(_safe_mode & LAST_JAVA_PC)) {
uintptr_t &sp = vm_thread->lastJavaSP();
uintptr_t &pc = vm_thread->lastJavaPC();
if (sp != 0 && pc == 0) {
// We have the last Java frame anchor, but it is not marked as walkable.
// Make it walkable here
pc = ((uintptr_t *)sp)[-1];
NMethod *m = CodeHeap::findNMethod((const void *)pc);
if (m != NULL) {
// AGCT fails if the last Java frame is a Runtime Stub with an invalid
// _frame_complete_offset. In this case we patch _frame_complete_offset
// manually
if (!m->isNMethod() && m->frameSize() > 0 &&
m->frameCompleteOffset() == -1) {
m->setFrameCompleteOffset(0);
}
VM::_asyncGetCallTrace(&trace, max_depth, ucontext);
} else if (findLibraryByAddress((const void *)pc) != NULL) {
VM::_asyncGetCallTrace(&trace, max_depth, ucontext);
}
pc = 0;
}
} else if (trace.num_frames == ticks_not_walkable_not_Java &&
!(_safe_mode & LAST_JAVA_PC)) {
uintptr_t &sp = vm_thread->lastJavaSP();
uintptr_t &pc = vm_thread->lastJavaPC();
if (sp != 0 && pc != 0) {
// Similar to the above: last Java frame is set,
// but points to a Runtime Stub with an invalid _frame_complete_offset
NMethod *m = CodeHeap::findNMethod((const void *)pc);
if (m != NULL && !m->isNMethod() && m->frameSize() > 0 &&
m->frameCompleteOffset() == -1) {
m->setFrameCompleteOffset(0);
VM::_asyncGetCallTrace(&trace, max_depth, ucontext);
}
}
} else if (trace.num_frames == ticks_GC_active && !(_safe_mode & GC_TRACES)) {
if (vm_thread->lastJavaSP() == 0) {
// Do not add 'GC_active' for threads with no Java frames, e.g. Compiler
// threads
frame.restore(saved_pc, saved_sp, saved_fp);
return 0;
}
}
frame.restore(saved_pc, saved_sp, saved_fp);
if (trace.num_frames > 0) {
return trace.num_frames + (trace.frames - frames);
}
const char *err_string = asgctError(trace.num_frames);
if (err_string == NULL) {
// No Java stack, because thread is not in Java context
return 0;
}
atomicInc(_failures[-trace.num_frames]);
trace.frames->bci = BCI_ERROR;
trace.frames->method_id = (jmethodID)err_string;
return trace.frames - frames + 1;
}
int Profiler::getJavaTraceJvmti(jvmtiFrameInfo *jvmti_frames,
ASGCT_CallFrame *frames, int start_depth,
int max_depth) {
int num_frames;
if (VM::jvmti()->GetStackTrace(NULL, start_depth, _max_stack_depth,
jvmti_frames, &num_frames) == 0 &&
num_frames > 0) {
return convertFrames(jvmti_frames, frames, num_frames);
}
return 0;
}
int Profiler::getJavaTraceInternal(jvmtiFrameInfo *jvmti_frames,
ASGCT_CallFrame *frames, int max_depth) {
// We cannot call pure JVM TI here, because it assumes _thread_in_native
// state, but allocation events happen in _thread_in_vm state, see
// https://github.com/jvm-profiling-tools/java-profiler/issues/64
JNIEnv *jni = VM::jni();
if (jni == NULL) {
return 0;
}
JitWriteProtection jit(false);
VMThread *vm_thread = VMThread::fromEnv(jni);
int num_frames;
if (VMStructs::_get_stack_trace(NULL, vm_thread, 0, max_depth, jvmti_frames,
&num_frames) == 0 &&
num_frames > 0) {
return convertFrames(jvmti_frames, frames, num_frames);
}
return 0;
}
inline int Profiler::convertFrames(jvmtiFrameInfo *jvmti_frames,
ASGCT_CallFrame *frames, int num_frames) {
// Convert to AsyncGetCallTrace format.
// Note: jvmti_frames and frames may overlap.
for (int i = 0; i < num_frames; i++) {
jint bci = jvmti_frames[i].location;
frames[i].method_id = jvmti_frames[i].method;
frames[i].bci = bci;
}
return num_frames;
}
void Profiler::fillFrameTypes(ASGCT_CallFrame *frames, int num_frames,
NMethod *nmethod) {
if (nmethod->isNMethod() && nmethod->isAlive()) {
VMMethod *method = nmethod->method();
if (method == NULL) {
return;
}
jmethodID current_method_id = method->id();
if (current_method_id == NULL) {
return;
}
// Mark current_method as COMPILED and frames above current_method as
// INLINED
for (int i = 0; i < num_frames; i++) {
if (frames[i].method_id == NULL || frames[i].bci <= BCI_NATIVE_FRAME) {
break;
}
if (frames[i].method_id == current_method_id) {
int level = nmethod->level();
frames[i].bci = FrameType::encode(
level >= 1 && level <= 3 ? FRAME_C1_COMPILED : FRAME_JIT_COMPILED,
frames[i].bci);
for (int j = 0; j < i; j++) {
frames[j].bci = FrameType::encode(FRAME_INLINED, frames[j].bci);
}
break;
}
}
} else if (nmethod->isInterpreter()) {
// Mark the first Java frame as INTERPRETED
for (int i = 0; i < num_frames; i++) {
if (frames[i].bci > BCI_NATIVE_FRAME) {
frames[i].bci = FrameType::encode(FRAME_INTERPRETED, frames[i].bci);
break;
}
}
}
}
void Profiler::recordExternalSample(u64 counter, int tid,
jvmtiFrameInfo *jvmti_frames,
jint num_jvmti_frames, bool truncated,
jint event_type, Event *event) {
atomicInc(_total_samples);
u32 lock_index = getLockIndex(tid);
if (!_locks[lock_index].tryLock() &&
!_locks[lock_index = (lock_index + 1) % CONCURRENCY_LEVEL].tryLock() &&
!_locks[lock_index = (lock_index + 2) % CONCURRENCY_LEVEL].tryLock()) {
// Too many concurrent signals already
atomicInc(_failures[-ticks_skipped]);
if (event_type == BCI_CPU && _cpu_engine == &perf_events) {
// Need to reset PerfEvents ring buffer, even though we discard the
// collected trace
PerfEvents::resetBuffer(tid);
}
return;
}
u32 call_trace_id = 0;
if (!_omit_stacktraces && jvmti_frames != nullptr) {
ASGCT_CallFrame *frames = _calltrace_buffer[lock_index]->_asgct_frames;
int num_frames = 0;
if (!_jfr.active() && BCI_ALLOC >= event_type && event_type >= BCI_PARK &&
event->_id) {
num_frames = makeFrame(frames, event_type, event->_id);
}
num_frames +=
convertFrames(jvmti_frames, frames + num_frames, num_jvmti_frames);
call_trace_id =
_call_trace_storage.put(num_frames, frames, truncated, counter);
}
_jfr.recordEvent(lock_index, tid, call_trace_id, event_type, event);
_locks[lock_index].unlock();
}
void Profiler::recordSample(void *ucontext, u64 counter, int tid,
jint event_type, u32 call_trace_id, Event *event) {
atomicInc(_total_samples);
u32 lock_index = getLockIndex(tid);
if (!_locks[lock_index].tryLock() &&
!_locks[lock_index = (lock_index + 1) % CONCURRENCY_LEVEL].tryLock() &&
!_locks[lock_index = (lock_index + 2) % CONCURRENCY_LEVEL].tryLock()) {
// Too many concurrent signals already
atomicInc(_failures[-ticks_skipped]);
if (event_type == BCI_CPU && _cpu_engine == &perf_events) {
// Need to reset PerfEvents ring buffer, even though we discard the
// collected trace
PerfEvents::resetBuffer(tid);
}
return;
}
bool truncated = false;
// in lightweight mode we're just sampling the the context associated with the
// passage of CPU or wall time, we use the same event definitions but we
// record a null stacktrace we can skip the unwind if we've got a
// call_trace_id determined to be reusable at a higher level
if (!_omit_stacktraces && call_trace_id == 0) {
ASGCT_CallFrame *frames = _calltrace_buffer[lock_index]->_asgct_frames;
int num_frames = 0;
StackContext java_ctx = {0};
ASGCT_CallFrame *native_stop = frames + num_frames;
num_frames += getNativeTrace(ucontext, native_stop, event_type, tid,
&java_ctx, &truncated);
if (_cstack == CSTACK_VM) {
num_frames +=
StackWalker::walkVM(ucontext, frames + num_frames, _max_stack_depth,
_call_stub_begin, _call_stub_end);
} else if (event_type == BCI_CPU || event_type == BCI_WALL) {
int java_frames = 0;
{
// Async events
AsyncSampleMutex mutex(ProfiledThread::current());
if (mutex.acquired()) {
java_frames =
getJavaTraceAsync(ucontext, frames + num_frames, _max_stack_depth,
&java_ctx, &truncated);
}
}
if (java_frames > 0 && java_ctx.pc != NULL) {
NMethod *nmethod = CodeHeap::findNMethod(java_ctx.pc);
if (nmethod != NULL) {
fillFrameTypes(frames + num_frames, java_frames, nmethod);
}
}
num_frames += java_frames;
}
if (num_frames == 0) {
num_frames += makeFrame(frames + num_frames, BCI_ERROR, "no_Java_frame");
}
call_trace_id =
_call_trace_storage.put(num_frames, frames, truncated, counter);
ProfiledThread *thread = ProfiledThread::current();
if (thread != nullptr) {
thread->recordCallTraceId(call_trace_id);
}
}
_jfr.recordEvent(lock_index, tid, call_trace_id, event_type, event);
_locks[lock_index].unlock();
}
void Profiler::recordWallClockEpoch(int tid, WallClockEpochEvent *event) {
u32 lock_index = getLockIndex(tid);
if (!_locks[lock_index].tryLock() &&
!_locks[lock_index = (lock_index + 1) % CONCURRENCY_LEVEL].tryLock() &&
!_locks[lock_index = (lock_index + 2) % CONCURRENCY_LEVEL].tryLock()) {
return;
}
_jfr.wallClockEpoch(lock_index, event);
_locks[lock_index].unlock();
}
void Profiler::recordTraceRoot(int tid, TraceRootEvent *event) {
u32 lock_index = getLockIndex(tid);
if (!_locks[lock_index].tryLock() &&
!_locks[lock_index = (lock_index + 1) % CONCURRENCY_LEVEL].tryLock() &&
!_locks[lock_index = (lock_index + 2) % CONCURRENCY_LEVEL].tryLock()) {
return;
}
_jfr.recordTraceRoot(lock_index, tid, event);
_locks[lock_index].unlock();
}
void Profiler::recordQueueTime(int tid, QueueTimeEvent *event) {
u32 lock_index = getLockIndex(tid);
if (!_locks[lock_index].tryLock() &&
!_locks[lock_index = (lock_index + 1) % CONCURRENCY_LEVEL].tryLock() &&
!_locks[lock_index = (lock_index + 2) % CONCURRENCY_LEVEL].tryLock()) {
return;
}
_jfr.recordQueueTime(lock_index, tid, event);
_locks[lock_index].unlock();
}
void Profiler::recordExternalSample(u64 weight, int tid, int num_frames,
ASGCT_CallFrame *frames, bool truncated,
jint event_type, Event *event) {
atomicInc(_total_samples);
u32 call_trace_id =
_call_trace_storage.put(num_frames, frames, truncated, weight);
u32 lock_index = getLockIndex(tid);
if (!_locks[lock_index].tryLock() &&
!_locks[lock_index = (lock_index + 1) % CONCURRENCY_LEVEL].tryLock() &&
!_locks[lock_index = (lock_index + 2) % CONCURRENCY_LEVEL].tryLock()) {
// Too many concurrent signals already
atomicInc(_failures[-ticks_skipped]);
return;
}
_jfr.recordEvent(lock_index, tid, call_trace_id, event_type, event);
_locks[lock_index].unlock();
}
void Profiler::writeLog(LogLevel level, const char *message) {
_jfr.recordLog(level, message, strlen(message));
}
void Profiler::writeLog(LogLevel level, const char *message, size_t len) {
_jfr.recordLog(level, message, len);
}
void Profiler::writeDatadogProfilerSetting(int tid, int length,
const char *name, const char *value,
const char *unit) {
u32 lock_index = getLockIndex(tid);
if (!_locks[lock_index].tryLock() &&
!_locks[lock_index = (lock_index + 1) % CONCURRENCY_LEVEL].tryLock() &&
!_locks[lock_index = (lock_index + 2) % CONCURRENCY_LEVEL].tryLock()) {
return;
}
_jfr.recordDatadogSetting(lock_index, length, name, value, unit);
_locks[lock_index].unlock();
}
void Profiler::writeHeapUsage(long value, bool live) {
int tid = ProfiledThread::currentTid();
if (tid < 0) {
return;
}
u32 lock_index = getLockIndex(tid);
if (!_locks[lock_index].tryLock() &&
!_locks[lock_index = (lock_index + 1) % CONCURRENCY_LEVEL].tryLock() &&
!_locks[lock_index = (lock_index + 2) % CONCURRENCY_LEVEL].tryLock()) {
return;
}
_jfr.recordHeapUsage(lock_index, value, live);
_locks[lock_index].unlock();
}
void *Profiler::dlopen_hook(const char *filename, int flags) {
void *result = dlopen(filename, flags);
if (result != NULL) {
instance()->updateSymbols(false);
}
return result;
}
void Profiler::switchLibraryTrap(bool enable) {
void *impl = enable ? (void *)dlopen_hook : (void *)dlopen;
__atomic_store_n(_dlopen_entry, impl, __ATOMIC_RELEASE);
}
void Profiler::enableEngines() {
_cpu_engine->enableEvents(true);
_wall_engine->enableEvents(true);
}
void Profiler::disableEngines() {
_cpu_engine->enableEvents(false);
_wall_engine->enableEvents(false);
}
void Profiler::segvHandler(int signo, siginfo_t *siginfo, void *ucontext) {
if (!crashHandler(signo, siginfo, ucontext)) {
orig_segvHandler(signo, siginfo, ucontext);
}
}
void Profiler::busHandler(int signo, siginfo_t *siginfo, void *ucontext) {
if (!crashHandler(signo, siginfo, ucontext)) {
orig_busHandler(signo, siginfo, ucontext);
}
}
bool Profiler::crashHandler(int signo, siginfo_t *siginfo, void *ucontext) {
ProfiledThread* thrd = ProfiledThread::current();
if (thrd != nullptr && !thrd->enterCrashHandler()) {
// we are already in a crash handler; don't recurse!
return false;
}
uintptr_t fault_address = (uintptr_t)siginfo->si_addr;
StackFrame frame(ucontext);
uintptr_t pc = frame.pc();
if (pc == fault_address) {
// it is 'pc' that is causing the fault; can not access it safely
if (thrd != nullptr) {
thrd->exitCrashHandler();
}
return false;
}
uintptr_t length = SafeAccess::skipLoad(pc);
if (length > 0) {
// Skip the fault instruction, as if it successfully loaded NULL
frame.pc() += length;
frame.retval() = 0;
if (thrd != nullptr) {
thrd->exitCrashHandler();
}
return true;
}
length = SafeAccess::skipLoadArg(pc);
if (length > 0) {
// Act as if the load returned default_value argument
frame.pc() += length;
frame.retval() = frame.arg1();
if (thrd != nullptr) {
thrd->exitCrashHandler();
}
return true;
}
if (WX_MEMORY && Trap::isFaultInstruction(pc)) {
if (thrd != nullptr) {
thrd->exitCrashHandler();
}
return true;
}
if (VM::isHotspot()) {
// the following checks require vmstructs and therefore HotSpot
StackWalker::checkFault(thrd);
// Workaround for JDK-8313796. Setting cstack=dwarf also helps
if (VMStructs::isInterpretedFrameValidFunc((const void *)pc) &&
frame.skipFaultInstruction()) {
if (thrd != nullptr) {
thrd->exitCrashHandler();
}
return true;
}
}
if (thrd != nullptr) {
thrd->exitCrashHandler();
}
return false;
}
void Profiler::setupSignalHandlers() {
// do not re-run the signal setup (run only when VM has not been loaded yet)
if (VM::java_version() > 0 && !VM::loaded()) {
// HotSpot and J9 tolerate interposed SIGSEGV/SIGBUS handler; other JVMs
// probably not
orig_segvHandler = OS::replaceSigsegvHandler(segvHandler);
orig_busHandler = OS::replaceSigbusHandler(busHandler);
}
}
/**
* Update thread name for the given thread
*/
void Profiler::updateThreadName(jvmtiEnv *jvmti, JNIEnv *jni, jthread thread,
bool self) {
JitWriteProtection jit(true); // workaround for JDK-8262896
jvmtiThreadInfo thread_info;
int native_thread_id = VMThread::nativeThreadId(jni, thread);
if (native_thread_id < 0 && self) {
// if updating the current thread, use the native thread id from the
// ProfilerThread
native_thread_id = ProfiledThread::currentTid();
}
if (native_thread_id >= 0 &&
jvmti->GetThreadInfo(thread, &thread_info) == 0) {
jlong java_thread_id = VMThread::javaThreadId(jni, thread);
_thread_info.set(native_thread_id, thread_info.name, java_thread_id);
jvmti->Deallocate((unsigned char *)thread_info.name);
}
}
void Profiler::updateJavaThreadNames() {
jvmtiEnv *jvmti = VM::jvmti();
jint thread_count;
jthread *thread_objects;