JDK-6639341 : sometimes contended-exit event comes after contended-entered on another thread
- Type: Bug
- Component: hotspot
- Sub-Component: runtime
- Affected Version: 7
- Priority: P3
- Status: Closed
- Resolution: Fixed
- OS: generic
- CPU: generic
- Submitted: 2007-12-08
- Updated: 2012-10-08
- Resolved: 2009-01-30
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| JDK 6 | JDK 7 | Other |
|---|---|---|
6u14Fixed  |
7Fixed |
hs14Fixed |
Description
With help of the D-Light tool I can see that the contended-exit events
comes after contended-entered event on another thread.
This is an example:
t12:Enter, t14:Enter, t2:Exit, t14:Entered, (t14:Exit is missed), t12:Entered
The tool does not show the t14:Exit event as it is already out of scope.
It happens because the Hotspot monitor-contended-exit probe is located incorrectly.
I think that posting the contended__exit monitor probe needs to be done
before wakee is unparked:
void ObjectMonitor::ExitEpilog (Thread * Self, ObjectWaiter * Wakee) {
...
Trigger->unpark() ;
// Maintain stats and report events to JVMTI
if (ObjectSynchronizer::_sync_Parks != NULL) {
ObjectSynchronizer::_sync_Parks->inc() ;
}
DTRACE_MONITOR_PROBE(contended__exit, this, object(), Self);
}
Comments
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