RFR: 8307365: JvmtiStressModule hit SIGSEGV in JvmtiEventControllerPrivate::recompute_thread_enabled [v2]

Tue May 16 20:26:48 UTC 2023

On Tue, 16 May 2023 20:13:38 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

> Summary: Thumbs up. This is most definitely NOT a trivial fix.
> 
> Normally the way I like to review these kinds of fixes is to map the failure modes back to the fix just to make sure I understand how each of the failure modes is covered by the changes. For this particular bug that has NOT been an easy thing to do. I believe the failure modes are complicated to follow because we "lost" the synchronization of being in the `VTMS_unmount_begin` transition which allowed a thread calling `recompute_enabled()` to race with our ending/exiting vthread/cthread combo. Ouch.
> 
Exactly. In the reproducer I aimed for the ThreadsListHandle crash, but while working on it I also hit the other ones.

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PR Comment: https://git.openjdk.org/jdk/pull/13949#issuecomment-1550308163