8233375: JFR emergency dump does not recover thread state
Reviewed-by: dholmes, mgronlun
--- a/src/hotspot/share/jfr/recorder/repository/jfrEmergencyDump.cpp Wed Nov 06 13:43:25 2019 +0800
+++ b/src/hotspot/share/jfr/recorder/repository/jfrEmergencyDump.cpp Wed Nov 06 21:49:30 2019 +0900
@@ -332,11 +332,7 @@
/*
* We are just about to exit the VM, so we will be very aggressive
-* at this point in order to increase overall success of dumping jfr data:
-*
-* 1. if the thread state is not "_thread_in_vm", we will quick transition
-* it to "_thread_in_vm".
-* 2. if the thread is the owner of some critical lock(s), unlock them.
+* at this point in order to increase overall success of dumping jfr data.
*
* If we end up deadlocking in the attempt of dumping out jfr data,
* we rely on the WatcherThread task "is_error_reported()",
@@ -344,19 +340,16 @@
* This "safety net" somewhat explains the aggressiveness in this attempt.
*
*/
-static bool prepare_for_emergency_dump() {
- if (JfrStream_lock->owned_by_self()) {
- // crashed during jfr rotation, disallow recursion
- return false;
- }
- Thread* const thread = Thread::current();
+static bool prepare_for_emergency_dump(Thread* thread) {
+ assert(thread != NULL, "invariant");
+
if (thread->is_Watcher_thread()) {
// need WatcherThread as a safeguard against potential deadlocks
return false;
}
-
- if (thread->is_Java_thread()) {
- ((JavaThread*)thread)->set_thread_state(_thread_in_vm);
+ if (JfrStream_lock->owned_by_self()) {
+ // crashed during jfr rotation, disallow recursion
+ return false;
}
#ifdef ASSERT
@@ -428,10 +421,43 @@
return Atomic::cmpxchg(1, &jfr_shutdown_lock, 0) == 0;
}
+class JavaThreadInVM : public StackObj {
+ private:
+ JavaThread* const _jt;
+ JavaThreadState _original_state;
+ public:
+
+ JavaThreadInVM(Thread* t) : _jt(t->is_Java_thread() ? (JavaThread*)t : NULL),
+ _original_state(_thread_max_state) {
+ if ((_jt != NULL) && (_jt->thread_state() != _thread_in_vm)) {
+ _original_state = _jt->thread_state();
+ _jt->set_thread_state(_thread_in_vm);
+ }
+ }
+
+ ~JavaThreadInVM() {
+ if (_original_state != _thread_max_state) {
+ _jt->set_thread_state(_original_state);
+ }
+ }
+
+};
+
void JfrEmergencyDump::on_vm_shutdown(bool exception_handler) {
- if (!(guard_reentrancy() && prepare_for_emergency_dump())) {
+ if (!guard_reentrancy()) {
return;
}
+
+ Thread* thread = Thread::current_or_null_safe();
+ if (thread == NULL) {
+ return;
+ }
+ // Ensure a JavaThread is _thread_in_vm when we make this call
+ JavaThreadInVM jtivm(thread);
+ if (!prepare_for_emergency_dump(thread)) {
+ return;
+ }
+
EventDumpReason event;
if (event.should_commit()) {
event.set_reason(exception_handler ? "Crash" : "Out of Memory");