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

[Jaroslav Bachorik]

On 29.1.2015 14:43, shanliang wrote:
> 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-
>   77     private static void waitForThreadState(Thread t, Thread.State
> state) throws InterruptedException {
>   78         while (!t.isInterrupted() && t.getState() != state) {
>   79             Thread.sleep(3);
>   80         }
>   81     }
> Better to throw an exception if t.isInterrupted()?
> Not sure when will happen t.isInterrupted(), but the method
> waitForThreadState tests it, so it is supposed to be possible to get it,
> when it is true then the testing method might return with a thread state
> different to the waited one.

Yes, it might get to an undefined state. But given that the thread would 
get interrupted only when the harness is timing out the test this 
discrepancy would not actually matter - the test would fail with timeout 
anyway.

-JB-

>
> Shanliang
>
>