RFR: 8308429: jvmti/StopThread/stopthrd007 failed with "NoClassDefFoundError: Could not initialize class jdk.internal.misc.VirtualThreads" [v2]

[David Holmes]

On Thu, 28 Sep 2023 21:04:58 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

>> The test fails because ThreadDeath is raised during class jdk.internal.misc.VirtualThreads initialization. The proposed fix is to pre-initialize this step to avoid such failures. See more details in the bug.
>> I reproduced the original problem and verified that it is not reproduced after fix. 
>> Tested with tier5 and running nsk/jvmti tests with and without virtual test thread factory.
>> 
>> I don't think that more complex fix is needed. There is a plan to review nsk/jvmti stopThread tests and see if 
>> ./serviceability/jvmti/vthread/StopThreadTest/StopThreadTest.java 
>> might be improved to cover them.
>
> Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:
> 
>   missed import added.

This is a reasonable workaround but I think there is a problem with the VirtualThread code that should be changed as well (or even instead). That code should be balanced in park/unpark paths such that any classloading happens on the park path IMO.

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Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/15966#pullrequestreview-1649889077