RFR 8071641: java/lang/management/ThreadMXBean/SynchronizationStatistics.java intermittently failed with NPE

[Jaroslav Bachorik]

On 29.1.2015 14:58, Daniel Fuchs wrote:
> Hi Jaroslav,
>
> The only thread state that this test is waiting on seems to be
> Thread.State.BLOCKED - which makes me wonder if you could add a
> method:
>
> String waitForBlockedState(Thread t) throws InterruptedException {
>     long tid = lt.getId();
>     ThreadInfo ti;
>     while ( (ti = mbean.getThreadInfo(tid)).getThreadState() !=
> Thread.State.BLOCKED) {
>        Thread.sleep(3);
>     }
>     return ti.getLockName();
> }

Retrieving ThreadInfo is a rather extensive operation involving security 
checks and as such might interfere with the test. It would require a 
thorough analysis to prove that it wouldn't interfere with the counters 
the test checks in any situation.

-JB-

>
> Would that be feasible - or would it have side effects on what the
> test is testing?
>
> best regards,
>
> -- daniel
>
> On 29/01/15 14:03, Jaroslav Bachorik wrote:
>> Please, review the following test change.
>>
>> Issue : https://bugs.openjdk.java.net/browse/JDK-8071641
>> Webrev: http://cr.openjdk.java.net/~jbachorik/8071641/webrev.00/
>>
>> The test fails very intermittently with NPE. This seems to be caused by
>> a data race between Thread.getStatus() and ThreadMXBean.getThreadInfo()
>> - thread state is reported as BLOCKED but the ThreadInfo still contains
>> a stale information (lockname == null).
>>
>> The solution would be re-retrieving the ThreadInfo until it reflects the
>> actual thread state.
>>
>> -JB-
>