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

[Chris Hegarty]

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>