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8021335: Missing synchronization when reading counters for live threads and peak thread count

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Reviewed-by: dholmes, mchung
This commit is contained in:
Dean Long 2018-10-25 18:41:26 -07:00
parent 7533f9f78a
commit c24f6506e7
4 changed files with 96 additions and 47 deletions
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100
src/hotspot/share/services/threadService.cpp
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@ -57,8 +57,8 @@ PerfCounter* ThreadService::_total_threads_count = NULL;
PerfVariable* ThreadService::_live_threads_count = NULL;
PerfVariable* ThreadService::_peak_threads_count = NULL;
PerfVariable* ThreadService::_daemon_threads_count = NULL;
volatile int ThreadService::_exiting_threads_count = 0;
volatile int ThreadService::_exiting_daemon_threads_count = 0;
volatile int ThreadService::_atomic_threads_count = 0;
volatile int ThreadService::_atomic_daemon_threads_count = 0;
ThreadDumpResult* ThreadService::_threaddump_list = NULL;
@ -101,50 +101,104 @@ void ThreadService::reset_peak_thread_count() {
_peak_threads_count->set_value(get_live_thread_count());
}
static bool is_hidden_thread(JavaThread *thread) {
// hide VM internal or JVMTI agent threads
return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread();
}
void ThreadService::add_thread(JavaThread* thread, bool daemon) {
// Do not count VM internal or JVMTI agent threads
if (thread->is_hidden_from_external_view() ||
thread->is_jvmti_agent_thread()) {
assert(Threads_lock->owned_by_self(), "must have threads lock");
// Do not count hidden threads
if (is_hidden_thread(thread)) {
return;
}
_total_threads_count->inc();
_live_threads_count->inc();
Atomic::inc(&_atomic_threads_count);
int count = _atomic_threads_count;
if (_live_threads_count->get_value() > _peak_threads_count->get_value()) {
_peak_threads_count->set_value(_live_threads_count->get_value());
if (count > _peak_threads_count->get_value()) {
_peak_threads_count->set_value(count);
}
if (daemon) {
_daemon_threads_count->inc();
Atomic::inc(&_atomic_daemon_threads_count);
}
}
void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) {
Atomic::dec(&_atomic_threads_count);
if (daemon) {
Atomic::dec(&_atomic_daemon_threads_count);
}
}
void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
Atomic::dec(&_exiting_threads_count);
if (daemon) {
Atomic::dec(&_exiting_daemon_threads_count);
}
assert(Threads_lock->owned_by_self(), "must have threads lock");
if (thread->is_hidden_from_external_view() ||
thread->is_jvmti_agent_thread()) {
// Do not count hidden threads
if (is_hidden_thread(thread)) {
return;
}
_live_threads_count->set_value(_live_threads_count->get_value() - 1);
if (daemon) {
_daemon_threads_count->set_value(_daemon_threads_count->get_value() - 1);
assert(!thread->is_terminated(), "must not be terminated");
if (!thread->is_exiting()) {
// JavaThread::exit() skipped calling current_thread_exiting()
decrement_thread_counts(thread, daemon);
}
int daemon_count = _atomic_daemon_threads_count;
int count = _atomic_threads_count;
// Counts are incremented at the same time, but atomic counts are
// decremented earlier than perf counts.
assert(_live_threads_count->get_value() > count,
"thread count mismatch %d : %d",
(int)_live_threads_count->get_value(), count);
_live_threads_count->dec(1);
if (daemon) {
assert(_daemon_threads_count->get_value() > daemon_count,
"thread count mismatch %d : %d",
(int)_daemon_threads_count->get_value(), daemon_count);
_daemon_threads_count->dec(1);
}
// Counts are incremented at the same time, but atomic counts are
// decremented earlier than perf counts.
assert(_daemon_threads_count->get_value() >= daemon_count,
"thread count mismatch %d : %d",
(int)_daemon_threads_count->get_value(), daemon_count);
assert(_live_threads_count->get_value() >= count,
"thread count mismatch %d : %d",
(int)_live_threads_count->get_value(), count);
assert(_live_threads_count->get_value() > 0 ||
(_live_threads_count->get_value() == 0 && count == 0 &&
_daemon_threads_count->get_value() == 0 && daemon_count == 0),
"thread counts should reach 0 at the same time, live %d,%d daemon %d,%d",
(int)_live_threads_count->get_value(), count,
(int)_daemon_threads_count->get_value(), daemon_count);
assert(_daemon_threads_count->get_value() > 0 ||
(_daemon_threads_count->get_value() == 0 && daemon_count == 0),
"thread counts should reach 0 at the same time, daemon %d,%d",
(int)_daemon_threads_count->get_value(), daemon_count);
}
void ThreadService::current_thread_exiting(JavaThread* jt) {
assert(jt == JavaThread::current(), "Called by current thread");
Atomic::inc(&_exiting_threads_count);
oop threadObj = jt->threadObj();
if (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)) {
Atomic::inc(&_exiting_daemon_threads_count);
void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) {
// Do not count hidden threads
if (is_hidden_thread(jt)) {
return;
}
assert(jt == JavaThread::current(), "Called by current thread");
assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting");
decrement_thread_counts(jt, daemon);
}
// FIXME: JVMTI should call this function