RFR: 8343953: Test jdk/jfr/threading/TestDeepVirtualStackTrace.java fails with Parallel/Serial GC [v2]

[Hamlin Li]

On Wed, 13 Nov 2024 17:12:30 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

>> Test fails because it doesn't always trigger jdk.ObjectAllocationOutsideTLAB event.
>> 
>> Test tries to trigger jdk.ObjectAllocationOutsideTLAB by allocating 
>> new Object[10_000_000];
>> array.
>> 
>> However, the TLAB is not limited for Parallel/Serial/Z GCs. So VM might just increase TLAB and allocate the array in new TLAB. The fix limit young generation size to ensure that TLAB of expected size can't be created and
>>  jdk.ObjectAllocationOutsideTLAB  event is always generated.
>> Verified by running 100 times with Parallel/Serial/ZGC on different platforms.
>> 
>> Using  jdk.ObjectAllocationOutsideTLAB is not  the signifcant for the test. The better fix would be trigger some other event with 100% guarantee assuming that this event is not triggered outside of virtual thread. But not sure I which event is the good candidate.
>
> Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:
> 
>   added comment

Looks good, Thanks!

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Marked as reviewed by mli (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22052#pullrequestreview-2434158372