1.1 --- a/src/share/vm/prims/jvmtiEnvBase.cpp Wed Feb 27 16:40:30 2013 +0000
1.2 +++ b/src/share/vm/prims/jvmtiEnvBase.cpp Wed Feb 27 15:00:30 2013 -0800
1.3 @@ -997,13 +997,19 @@
1.4 // move our object at this point. However, our owner value is safe
1.5 // since it is either the Lock word on a stack or a JavaThread *.
1.6 owning_thread = Threads::owning_thread_from_monitor_owner(owner, !at_safepoint);
1.7 - assert(owning_thread != NULL, "sanity check");
1.8 - if (owning_thread != NULL) { // robustness
1.9 + // Cannot assume (owning_thread != NULL) here because this function
1.10 + // may not have been called at a safepoint and the owning_thread
1.11 + // might not be suspended.
1.12 + if (owning_thread != NULL) {
1.13 // The monitor's owner either has to be the current thread, at safepoint
1.14 // or it has to be suspended. Any of these conditions will prevent both
1.15 // contending and waiting threads from modifying the state of
1.16 // the monitor.
1.17 if (!at_safepoint && !JvmtiEnv::is_thread_fully_suspended(owning_thread, true, &debug_bits)) {
1.18 + // Don't worry! This return of JVMTI_ERROR_THREAD_NOT_SUSPENDED
1.19 + // will not make it back to the JVM/TI agent. The error code will
1.20 + // get intercepted in JvmtiEnv::GetObjectMonitorUsage() which
1.21 + // will retry the call via a VM_GetObjectMonitorUsage VM op.
1.22 return JVMTI_ERROR_THREAD_NOT_SUSPENDED;
1.23 }
1.24 HandleMark hm;
