RFR [7181748] TEST_BUG: java/lang/ThreadGroup/Suspend test fails intermittently

Ivan Gerasimov ivan.gerasimov at oracle.com
Tue Jun 11 14:13:36 UTC 2013

Chris and David, thanks for review.

I've updated the test so the threads use CountDownLatch to wait for each 
Now, instead of checking whether the 'second' thread has incremented a 
count, the 'main' thread waits for it to call countDown().
If a timeout was elapsed before the call, I assume that the 'second' 
thread is suspended and the test passes.

Could you please review the updated webrev:


On 11.06.2013 13:37, Chris Hegarty wrote:
> On 06/11/2013 08:08 AM, David Holmes wrote:
>> On 11/06/2013 1:54 AM, Chris Hegarty wrote:
>>> I'm not sure I ever saw this test fail, but it does look like it has
>>> issues.
>>> I would much prefer to see a j.u.c.Latch/Phaser used to synchronize
>>> across these threads.
>> I don't think that is possible. The main thread wants to reset the count
>> after the suspend has been issued by "first", but once the suspend has
>> been issued the "first" thread can't signal the synchronizer to let the
>> main thread proceed. The poll around isAlive() does address the main
>> issue of a slowly starting thread.
> Ah yes, thanks David. In which case I'm fine with the change.
>> For completeness the count variable should be volatile as well.
> Agreed.
> -Chris.
>> Cheers,
>> David
>>> -Chris.
>>> On 10/06/2013 13:51, Ivan Gerasimov wrote:
>>>> Hello everyone!
>>>> The test of ThreadGroup.Suspend() was reported to fail on rare
>>>> occasions.
>>>> It can happen on a busy machine that 1 second delay would not be 
>>>> enough
>>>> for the second thread to start.
>>>> Then the first thread would suspend only itself and the test would 
>>>> fail.
>>>> Earlier, another test was updated for similar reasons [1], [2].
>>>> The proposed test can still report false *positive* results if the
>>>> second thread has had no chance to execute during one second after it
>>>> had started.
>>>> To avoid them there must be a way do distinguish suspended threads.
>>>> WEBREV: http://cr.openjdk.java.net/~igerasim/7181748/webrev.0/
>>>> BUG: http://bugs.sun.com/view_bug.do?bug_id=7181748
>>>> [1] http://bugs.sun.com/view_bug.do?bug_id=7084033
>>>> [2] http://hg.openjdk.java.net/jdk8/jdk8/jdk/rev/184578f3e8b9
>>>> Sincerely yours,
>>>> Ivan Gerasimov
>>>> <https://jbs.oracle.com/bugs/browse/JDK-7084033>

More information about the core-libs-dev mailing list