void VM_ThreadDump::doit() {
ResourceMark rm;
ConcurrentLocksDump concurrent_locks(true);
if (_with_locked_synchronizers) {
concurrent_locks.dump_at_safepoint();
}
if (_num_threads == 0) {
// Snapshot all live threads
for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
if (jt->is_exiting() ||
jt->is_hidden_from_external_view()) {
// skip terminating threads and hidden threads
continue;
}
ThreadConcurrentLocks* tcl = NULL;
if (_with_locked_synchronizers) {
tcl = concurrent_locks.thread_concurrent_locks(jt);
}
ThreadSnapshot* ts = snapshot_thread(jt, tcl);
_result->add_thread_snapshot(ts);
}
} else {
// Snapshot threads in the given _threads array
// A dummy snapshot is created if a thread doesn't exist
for (int i = 0; i < _num_threads; i++) {
instanceHandle th = _threads->at(i);
if (th() == NULL) {
// skip if the thread doesn't exist
// Add a dummy snapshot
_result->add_thread_snapshot(new ThreadSnapshot());
continue;
}
// Dump thread stack only if the thread is alive and not exiting
// and not VM internal thread.
JavaThread* jt = java_lang_Thread::thread(th());
if (jt == NULL || /* thread not alive */
jt->is_exiting() ||
jt->is_hidden_from_external_view()) {
// add a NULL snapshot if skipped
_result->add_thread_snapshot(new ThreadSnapshot());
continue;
}
ThreadConcurrentLocks* tcl = NULL;
if (_with_locked_synchronizers) {
tcl = concurrent_locks.thread_concurrent_locks(jt);
}
ThreadSnapshot* ts = snapshot_thread(jt, tcl);
_result->add_thread_snapshot(ts);
}
}
}
void doit() {
ResourceMark rmark; // _thread != Thread::current()
RegisterMap rm(_thread, false);
// There can be a race condition between a VM_Operation reaching a safepoint
// and the target thread exiting from Java execution.
// We must recheck the last Java frame still exists.
if (!_thread->is_exiting() && _thread->has_last_Java_frame()) {
javaVFrame* vf = _thread->last_java_vframe(&rm);
assert(vf != NULL, "must have last java frame");
Method* method = vf->method();
_method_id = method->jmethod_id();
_bci = vf->bci();
} else {
// Clear current location as the target thread has no Java frames anymore.
_method_id = (jmethodID)NULL;
_bci = 0;
}
}
void FlatProfiler::record_thread_ticks() {
int maxthreads, suspendedthreadcount;
JavaThread** threadsList;
bool interval_expired = false;
if (ProfileIntervals &&
(FlatProfiler::received_ticks >= interval_ticks_previous + ProfileIntervalsTicks)) {
interval_expired = true;
interval_ticks_previous = FlatProfiler::received_ticks;
}
// Try not to wait for the Threads_lock
if (Threads_lock->try_lock()) {
{ // Threads_lock scope
maxthreads = Threads::number_of_threads();
threadsList = NEW_C_HEAP_ARRAY(JavaThread *, maxthreads, mtInternal);
suspendedthreadcount = 0;
for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
if (tp->is_Compiler_thread()) {
// Only record ticks for active compiler threads
CompilerThread* cthread = (CompilerThread*)tp;
if (cthread->task() != NULL) {
// The compiler is active. If we need to access any of the fields
// of the compiler task we should suspend the CompilerThread first.
FlatProfiler::compiler_ticks += 1;
continue;
}
}
// First externally suspend all threads by marking each for
// external suspension - so it will stop at its next transition
// Then do a safepoint
ThreadProfiler* pp = tp->get_thread_profiler();
if (pp != NULL && pp->engaged) {
MutexLockerEx ml(tp->SR_lock(), Mutex::_no_safepoint_check_flag);
if (!tp->is_external_suspend() && !tp->is_exiting()) {
tp->set_external_suspend();
threadsList[suspendedthreadcount++] = tp;
}
}
}
Threads_lock->unlock();
}
ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
bool include_jvmti_agent_threads,
bool include_jni_attaching_threads) {
assert(cur_thread == Thread::current(), "Check current thread");
int init_size = ThreadService::get_live_thread_count();
_threads_array = new GrowableArray<instanceHandle>(init_size);
MutexLockerEx ml(Threads_lock);
for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
// skips JavaThreads in the process of exiting
// and also skips VM internal JavaThreads
// Threads in _thread_new or _thread_new_trans state are included.
// i.e. threads have been started but not yet running.
if (jt->threadObj() == NULL ||
jt->is_exiting() ||
!java_lang_Thread::is_alive(jt->threadObj()) ||
jt->is_hidden_from_external_view()) {
continue;
}
// skip agent threads
if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
continue;
}
// skip jni threads in the process of attaching
if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
continue;
}
instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
_threads_array->append(h);
}
}
void AsyncGetCallTrace(ASGCT_CallTrace *trace, jint depth, void* ucontext) {
// This is if'd out because we no longer use thread suspension.
// However if someone wanted to backport this to a 5.0 jvm then this
// code would be important.
#if 0
if (SafepointSynchronize::is_synchronizing()) {
// The safepoint mechanism is trying to synchronize all the threads.
// Since this can involve thread suspension, it is not safe for us
// to be here. We can reduce the deadlock risk window by quickly
// returning to the SIGPROF handler. However, it is still possible
// for VMThread to catch us here or in the SIGPROF handler. If we
// are suspended while holding a resource and another thread blocks
// on that resource in the SIGPROF handler, then we will have a
// three-thread deadlock (VMThread, this thread, the other thread).
trace->num_frames = ticks_safepoint; // -10
return;
}
#endif
JavaThread* thread;
if (trace->env_id == NULL ||
(thread = JavaThread::thread_from_jni_environment(trace->env_id)) == NULL ||
thread->is_exiting()) {
// bad env_id, thread has exited or thread is exiting
trace->num_frames = ticks_thread_exit; // -8
return;
}
if (thread->in_deopt_handler()) {
// thread is in the deoptimization handler so return no frames
trace->num_frames = ticks_deopt; // -9
return;
}
assert(JavaThread::current() == thread,
"AsyncGetCallTrace must be called by the current interrupted thread");
if (!JvmtiExport::should_post_class_load()) {
trace->num_frames = ticks_no_class_load; // -1
return;
}
if (Universe::heap()->is_gc_active()) {
trace->num_frames = ticks_GC_active; // -2
return;
}
switch (thread->thread_state()) {
case _thread_new:
case _thread_uninitialized:
case _thread_new_trans:
// We found the thread on the threads list above, but it is too
// young to be useful so return that there are no Java frames.
trace->num_frames = 0;
break;
case _thread_in_native:
case _thread_in_native_trans:
case _thread_blocked:
case _thread_blocked_trans:
case _thread_in_vm:
case _thread_in_vm_trans:
{
frame fr;
// param isInJava == false - indicate we aren't in Java code
if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, false)) {
trace->num_frames = ticks_unknown_not_Java; // -3 unknown frame
} else {
if (!thread->has_last_Java_frame()) {
trace->num_frames = 0; // No Java frames
} else {
trace->num_frames = ticks_not_walkable_not_Java; // -4 non walkable frame by default
forte_fill_call_trace_given_top(thread, trace, depth, fr);
// This assert would seem to be valid but it is not.
// It would be valid if we weren't possibly racing a gc
// thread. A gc thread can make a valid interpreted frame
// look invalid. It's a small window but it does happen.
// The assert is left here commented out as a reminder.
// assert(trace->num_frames != ticks_not_walkable_not_Java, "should always be walkable");
}
}
}
break;
case _thread_in_Java:
case _thread_in_Java_trans:
{
frame fr;
// param isInJava == true - indicate we are in Java code
if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, true)) {
trace->num_frames = ticks_unknown_Java; // -5 unknown frame
} else {
trace->num_frames = ticks_not_walkable_Java; // -6, non walkable frame by default
forte_fill_call_trace_given_top(thread, trace, depth, fr);
}
}
break;
default:
// Unknown thread state
trace->num_frames = ticks_unknown_state; // -7
break;
}
}
JNIEXPORT
void AsyncGetCallTrace(ASGCT_CallTrace *trace, jint depth, void* ucontext) {
JavaThread* thread;
if (trace->env_id == NULL ||
(thread = JavaThread::thread_from_jni_environment(trace->env_id)) == NULL ||
thread->is_exiting()) {
// bad env_id, thread has exited or thread is exiting
trace->num_frames = ticks_thread_exit; // -8
return;
}
if (thread->in_deopt_handler()) {
// thread is in the deoptimization handler so return no frames
trace->num_frames = ticks_deopt; // -9
return;
}
assert(JavaThread::current() == thread,
"AsyncGetCallTrace must be called by the current interrupted thread");
if (!JvmtiExport::should_post_class_load()) {
trace->num_frames = ticks_no_class_load; // -1
return;
}
if (Universe::heap()->is_gc_active()) {
trace->num_frames = ticks_GC_active; // -2
return;
}
switch (thread->thread_state()) {
case _thread_new:
case _thread_uninitialized:
case _thread_new_trans:
// We found the thread on the threads list above, but it is too
// young to be useful so return that there are no Java frames.
trace->num_frames = 0;
break;
case _thread_in_native:
case _thread_in_native_trans:
case _thread_blocked:
case _thread_blocked_trans:
case _thread_in_vm:
case _thread_in_vm_trans:
{
frame fr;
// param isInJava == false - indicate we aren't in Java code
if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, false)) {
trace->num_frames = ticks_unknown_not_Java; // -3 unknown frame
} else {
if (!thread->has_last_Java_frame()) {
trace->num_frames = 0; // No Java frames
} else {
trace->num_frames = ticks_not_walkable_not_Java; // -4 non walkable frame by default
forte_fill_call_trace_given_top(thread, trace, depth, fr);
// This assert would seem to be valid but it is not.
// It would be valid if we weren't possibly racing a gc
// thread. A gc thread can make a valid interpreted frame
// look invalid. It's a small window but it does happen.
// The assert is left here commented out as a reminder.
// assert(trace->num_frames != ticks_not_walkable_not_Java, "should always be walkable");
}
}
}
break;
case _thread_in_Java:
case _thread_in_Java_trans:
{
frame fr;
// param isInJava == true - indicate we are in Java code
if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, true)) {
trace->num_frames = ticks_unknown_Java; // -5 unknown frame
} else {
trace->num_frames = ticks_not_walkable_Java; // -6, non walkable frame by default
forte_fill_call_trace_given_top(thread, trace, depth, fr);
}
}
break;
default:
// Unknown thread state
trace->num_frames = ticks_unknown_state; // -7
break;
}
}