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Merge pull request #19951 from gacholio/jfr
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Basic sampling thread for JFR
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@tajila
tajila authored Aug 12, 2024
2 parents d57675e + f84fbc7 commit 1cac505
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Showing 2 changed files with 117 additions and 6 deletions.
8 changes: 8 additions & 0 deletions runtime/oti/j9nonbuilder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -6147,6 +6147,9 @@ typedef struct J9JavaVM {
JFRState jfrState;
J9JFRBuffer jfrBuffer;
omrthread_monitor_t jfrBufferMutex;
omrthread_monitor_t jfrSamplerMutex;
omrthread_t jfrSamplerThread;
UDATA jfrSamplerState;
#endif /* defined(J9VM_OPT_JFR) */
#if JAVA_SPEC_VERSION >= 22
omrthread_monitor_t closeScopeMutex;
Expand All @@ -6155,6 +6158,11 @@ typedef struct J9JavaVM {
UDATA unsafeIndexableHeaderSize;
} J9JavaVM;

#define J9JFR_SAMPLER_STATE_UNINITIALIZED 0
#define J9JFR_SAMPLER_STATE_RUNNING 1
#define J9JFR_SAMPLER_STATE_STOP 2
#define J9JFR_SAMPLER_STATE_DEAD 3

#define J9VM_PHASE_STARTUP 1
#define J9VM_PHASE_NOT_STARTUP 2
#define J9VM_PHASE_LATE_SCC_DISCLAIM 3
Expand Down
115 changes: 109 additions & 6 deletions runtime/vm/jfr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,9 +32,10 @@ extern "C" {

#undef DEBUG

// TODO: allow different buffer sizes on different threads and configureable sizes
// TODO: allow configureable values
#define J9JFR_THREAD_BUFFER_SIZE (1024*1024)
#define J9JFR_GLOBAL_BUFFER_SIZE (10 * J9JFR_THREAD_BUFFER_SIZE)
#define J9JFR_SAMPLING_RATE 1000

static UDATA jfrEventSize(J9JFREvent *jfrEvent);
static void tearDownJFR(J9JavaVM *vm);
Expand All @@ -48,7 +49,9 @@ static void jfrClassesUnload(J9HookInterface **hook, UDATA eventNum, void *event
static void jfrVMShutdown(J9HookInterface **hook, UDATA eventNum, void *eventData, void *userData);
static void jfrThreadStarting(J9HookInterface **hook, UDATA eventNum, void *eventData, void *userData);
static void jfrThreadEnd(J9HookInterface **hook, UDATA eventNum, void *eventData, void *userData);
static void jfrVMInitialized(J9HookInterface **hook, UDATA eventNum, void *eventData, void *userData);
static void initializeEventFields(J9VMThread *currentThread, J9JFREvent *jfrEvent, UDATA eventType);
static int J9THREAD_PROC jfrSamplingThreadProc(void *entryArg);

/**
* Calculate the size in bytes of a JFR event.
Expand Down Expand Up @@ -496,6 +499,41 @@ jfrVMSleep(J9HookInterface **hook, UDATA eventNum, void *eventData, void *userDa
}
}

/**
* Hook for VM intialized. Called without VM access.
*
* @param hook[in] the VM hook interface
* @param eventNum[in] the event number
* @param eventData[in] the event data
* @param userData[in] the registered user data
*/
static void
jfrVMInitialized(J9HookInterface **hook, UDATA eventNum, void *eventData, void *userData)
{
J9VMInitEvent *event = (J9VMInitEvent *)eventData;
J9VMThread *currentThread = event->vmThread;
J9JavaVM *vm = currentThread->javaVM;

#if defined(DEBUG)
PORT_ACCESS_FROM_VMC(currentThread);
j9tty_printf(PORTLIB, "\n!!! VM init %p\n", currentThread);
#endif /* defined(DEBUG) */

/* Start the sampler thread */
if (0 == omrthread_create(&(vm->jfrSamplerThread), vm->defaultOSStackSize, J9THREAD_PRIORITY_NORMAL, FALSE, jfrSamplingThreadProc, (void*)vm)) {
omrthread_monitor_enter(vm->jfrSamplerMutex);
while (J9JFR_SAMPLER_STATE_UNINITIALIZED == vm->jfrSamplerState) {
omrthread_monitor_wait(vm->jfrSamplerMutex);
}
omrthread_monitor_exit(vm->jfrSamplerMutex);
if (J9JFR_SAMPLER_STATE_DEAD == vm->jfrSamplerState) {
// TODO: tracepoint?
}
} else {
// TODO: tracepoint?
}
}

jint
initializeJFR(J9JavaVM *vm)
{
Expand Down Expand Up @@ -525,8 +563,11 @@ initializeJFR(J9JavaVM *vm)
if ((*vmHooks)->J9HookRegisterWithCallSite(vmHooks, J9HOOK_VM_SLEEP, jfrVMSleep, OMR_GET_CALLSITE(), NULL)) {
goto fail;
}
if ((*vmHooks)->J9HookRegisterWithCallSite(vmHooks, J9HOOK_VM_INITIALIZED, jfrVMInitialized, OMR_GET_CALLSITE(), NULL)) {
goto fail;
}

/* Allocate the global buffer and mutex */
/* Allocate global data */
buffer = (U_8*)j9mem_allocate_memory(J9JFR_GLOBAL_BUFFER_SIZE, OMRMEM_CATEGORY_VM);
if (NULL == buffer) {
goto fail;
Expand All @@ -537,7 +578,10 @@ initializeJFR(J9JavaVM *vm)
vm->jfrBuffer.bufferRemaining = J9JFR_GLOBAL_BUFFER_SIZE;
vm->jfrState.jfrChunkCount = 0;
if (omrthread_monitor_init_with_name(&vm->jfrBufferMutex, 0, "JFR global buffer mutex")) {
goto done;
goto fail;
}
if (omrthread_monitor_init_with_name(&vm->jfrSamplerMutex, 0, "JFR sampler mutex")) {
goto fail;
}

if (!VM_JFRWriter::initializaJFRWriter(vm)) {
Expand All @@ -563,6 +607,21 @@ tearDownJFR(J9JavaVM *vm)
PORT_ACCESS_FROM_JAVAVM(vm);
J9HookInterface **vmHooks = getVMHookInterface(vm);

/* Stop the sampler thread */
if (NULL != vm->jfrSamplerMutex) {
omrthread_monitor_enter(vm->jfrSamplerMutex);
if (J9JFR_SAMPLER_STATE_RUNNING == vm->jfrSamplerState) {
vm->jfrSamplerState = J9JFR_SAMPLER_STATE_STOP;
omrthread_monitor_notify_all(vm->jfrSamplerMutex);
while (J9JFR_SAMPLER_STATE_DEAD != vm->jfrSamplerState) {
omrthread_monitor_wait(vm->jfrSamplerMutex);
}
}
omrthread_monitor_exit(vm->jfrSamplerMutex);
omrthread_monitor_destroy(vm->jfrSamplerMutex);
vm->jfrSamplerMutex = NULL;
}

VM_JFRWriter::teardownJFRWriter(vm);

/* Unhook all the events */
Expand All @@ -573,17 +632,18 @@ tearDownJFR(J9JavaVM *vm)
(*vmHooks)->J9HookUnregister(vmHooks, J9HOOK_VM_THREAD_STARTING, jfrThreadStarting, NULL);
(*vmHooks)->J9HookUnregister(vmHooks, J9HOOK_VM_THREAD_END, jfrThreadEnd, NULL);
(*vmHooks)->J9HookUnregister(vmHooks, J9HOOK_VM_SLEEP, jfrVMSleep, NULL);
(*vmHooks)->J9HookUnregister(vmHooks, J9HOOK_VM_INITIALIZED, jfrVMInitialized, NULL);

/* Free global buffer and mutex */

/* Free global data */
j9mem_free_memory((void*)vm->jfrBuffer.bufferStart);
memset(&vm->jfrBuffer, 0, sizeof(vm->jfrBuffer));
if (NULL != vm->jfrBufferMutex) {
omrthread_monitor_destroy(vm->jfrBufferMutex);
vm->jfrBufferMutex = NULL;
}
vm->jfrState.metaDataBlobFileSize = 0;
j9mem_free_memory(vm->jfrState.metaDataBlobFile);
vm->jfrState.metaDataBlobFile = NULL;
vm->jfrState.metaDataBlobFileSize = 0;
}

/**
Expand All @@ -602,15 +662,58 @@ initializeEventFields(J9VMThread *currentThread, J9JFREvent *event, UDATA eventT
event->vmThread = currentThread;
}

// TODO: add thread state parameter
void
jfrExecutionSample(J9VMThread *currentThread, J9VMThread *sampleThread)
{
#if defined(DEBUG)
PORT_ACCESS_FROM_VMC(currentThread);
j9tty_printf(PORTLIB, "\n!!! execution sample %p %p\n", currentThread, sampleThread);
#endif /* defined(DEBUG) */

J9JFRExecutionSample *jfrEvent = (J9JFRExecutionSample*)reserveBufferWithStackTrace(currentThread, sampleThread, J9JFR_EVENT_TYPE_EXECUTION_SAMPLE, sizeof(*jfrEvent));
if (NULL != jfrEvent) {
jfrEvent->threadState = J9JFR_THREAD_STATE_RUNNING;
}
}

static int J9THREAD_PROC
jfrSamplingThreadProc(void *entryArg)
{
J9JavaVM *vm = (J9JavaVM*)entryArg;
J9VMThread *currentThread = NULL;

if (JNI_OK == attachSystemDaemonThread(vm, &currentThread, "JFR sampler")) {
omrthread_monitor_enter(vm->jfrSamplerMutex);
vm->jfrSamplerState = J9JFR_SAMPLER_STATE_RUNNING;
omrthread_monitor_notify_all(vm->jfrSamplerMutex);
while (J9JFR_SAMPLER_STATE_STOP != vm->jfrSamplerState) {
omrthread_monitor_exit(vm->jfrSamplerMutex);
internalEnterVMFromJNI(currentThread);
acquireExclusiveVMAccess(currentThread);
J9VMThread *walkThread = J9_LINKED_LIST_START_DO(vm->mainThread);
while (NULL != walkThread) {
if (VM_VMHelpers::threadCanRunJavaCode(walkThread)) {
jfrExecutionSample(currentThread, walkThread);
}
walkThread = J9_LINKED_LIST_NEXT_DO(vm->mainThread, walkThread);
}
releaseExclusiveVMAccess(currentThread);
internalExitVMToJNI(currentThread);
omrthread_monitor_enter(vm->jfrSamplerMutex);
omrthread_monitor_wait_timed(vm->jfrSamplerMutex, J9JFR_SAMPLING_RATE, 0);
}
omrthread_monitor_exit(vm->jfrSamplerMutex);
DetachCurrentThread((JavaVM*)vm);
}

omrthread_monitor_enter(vm->jfrSamplerMutex);
vm->jfrSamplerState = J9JFR_SAMPLER_STATE_DEAD;
omrthread_monitor_notify_all(vm->jfrSamplerMutex);
omrthread_exit(vm->jfrSamplerMutex);
return 0;
}

} /* extern "C" */

#endif /* defined(J9VM_OPT_JFR) */

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