src/share/vm/services/threadService.cpp

rev 4818 : 8016304: ThreadMXBean.getDeadlockedThreads reports bogus deadlocks on JDK 8
Reviewed-by:

@@ -325,12 +325,14 @@
       waitingToLockBlocker = jt->current_park_blocker();
     }
     while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
       cycle->add_thread(currentThread);
       if (waitingToLockMonitor != NULL) {
+        address currentOwner = (address)waitingToLockMonitor->owner();
+        if (currentOwner != NULL) {
         currentThread = Threads::owning_thread_from_monitor_owner(
-                          (address)waitingToLockMonitor->owner(),
+                            currentOwner,
                           false /* no locking needed */);
         if (currentThread == NULL) {
           // This function is called at a safepoint so the JavaThread
           // that owns waitingToLockMonitor should be findable, but
           // if it is not findable, then the previous currentThread is

@@ -347,10 +349,11 @@
           }
           last = cycle;
           cycle = new DeadlockCycle();
           break;
         }
+        }
       } else {
         if (concurrent_locks) {
           if (waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
             oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
             currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;