RFR: 8062036: ConcurrentMarkThread::slt may be invoked before ConcurrentMarkThread::makeSurrogateLockerThread causing intermittent crashes

Bengt Rutisson bengt.rutisson at oracle.com
Tue Nov 11 13:09:48 UTC 2014


Hi Kim,

On 11/10/14 10:26 PM, Kim Barrett wrote:
> On Nov 10, 2014, at 7:57 AM, Bengt Rutisson <bengt.rutisson at oracle.com> wrote:
>> Thanks for splitting the tests up. They look fine to me now. Except that now that they are specialized I guess they could be moved into the test/gc/cms and test/gc/g1 folders.
> I thought about that, but felt that keeping the two closely related tests close together was better than separating them into the respective GC folders.
>
>> Is the  -XX:SurvivorAlignmentInBytes=2k really required for the test to fail without the patch? In that case I think it is not enough to ignore the test since I *think* Jon's idea to fix JDK-8060463 is to limit what values are allowed for SurvivorAlignmentInBytes. Jon would know more about that.
> I talked to Jon, and he confirmed that limiting the permitted values
> for SurvivorAlignmentInBytes to something sane was the intended
> approach.  So that is indeed a problem for my regression test.  That
> test was cribbed from the 8062036 reproducer.
>
> I have not yet been able to find an alternative trigger, though
> searching for one has led to some interesting spelunking. Of course,
> that doesn't mean there isn't an alternative; the number of options
> and their possible interactions gives a pretty large search space.
>
> To trigger for G1 we need to somehow cause the concurrent mark thread
> to perform a GC remark fairly early in VM initialization. My attempts
> to create that situation have so far resulted in being too late to hit
> the problematic window, or blowing up for other reasons (such as heap
> size just being too small).
>
> Much as I think tests are a good thing, I'm getting to the point of
> wondering whether a regression test for this is worth the effort.

Yes, I agree with you. We should probably just tag the bug with 
noreg-hard and leave it for now. That also relieves us of the burden to 
decide on which directory to put the tests in. ;)

Thanks for trying hard to fix the tests.

Bengt


>



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