RFR(S): 8152989: serviceability/tmtools/jstat/GcCauseTest02.java fails with OOME

[Per Liden]

Hi Jon,

On 2016-04-06 23:47, Jon Masamitsu wrote:
> Per,
>
>
> On 04/06/2016 02:32 AM, Per Liden wrote:
>> Summary: This patch updates the tests in serviceability/tmtools/jstat/
>> to use a fixed (and relatively small) heap size. Without this these
>> tests tend to run out of memory on machines with VM overcommit
>> disabled. This has happened in nightly testing.
>
> So this fix works because multiple tests running on the same machine
> does not over reserve memory because a small heap maximum is used?
>
> I can see how the fix works but I can see how it could fail on some machine
> (maybe small memory machine?) if too many tests are started.  Is there
> an agent mode JTREG that could be used to run the test in the same JVM?
> If that could be used I think if JTREG could be run, then the tests would
> run.  If JTREG cannot be run, then it's more obviously a setup problem.

I don't think we're executing more than one test at a time here, but 
jtreg can start more than one VM to run the test and there might be 
aurora agents etc running on the machine. We already have quite a few 
tests using -Xmx128 so it shouldn't be a problem with regards to small 
machines.

cheers,
Per

>
> Jon
>
>>
>> The patch also moves a misplaced @ignore tag and cleans out an unused
>> method.
>>
>> Testing: Without this patch I can easily get these tests to OOM on my
>> local workstation by just disabling VM overcommit. They pass with this
>> patch applied.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8152989
>> Webrev: http://cr.openjdk.java.net/~pliden/8152989/webrev.0/
>>
>> cheers,
>> Per
>>
>