src/share/vm/runtime/synchronizer.cpp

*** 1641,1650 ****
--- 1641,1654 ----
  
   public:
    ReleaseJavaMonitorsClosure(Thread* thread) : THREAD(thread) {}
    void do_monitor(ObjectMonitor* mid) {
      if (mid->owner() == THREAD) {
+       guarantee(!GuaranteeOnMonitorMismatch,
+                 err_msg("exiting JavaThread=" INTPTR_FORMAT
+                         " unexpectedly owns ObjectMonitor=" INTPTR_FORMAT,
+                         THREAD, mid));
        (void)mid->complete_exit(CHECK);
      }
    }
  };