RFR: 8345543: Test serviceability/jvmti/vthread/StopThreadTest/StopThreadTest.java failed: expected JVMTI_ERROR_OPAQUE_FRAME instead of: 0 [v5]

[David Holmes]

On Fri, 17 Jan 2025 05:52:15 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> The problem is that the state of the target `vthread` is changed to `BLOCKED` too early. It is done in a constructor of helper object `JavaThreadBlockedOnMonitorEnterState` which sets the state of `vthread` to `JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER`. The `vthread` is getting suspended in `try_preempt()` while calling `JvmtiVTMSTransitionDisabler::start_VTMS_transition()`, so does not become unmounted as it is expected by the failing test. Also, it seems that the base class of the `JavaThreadBlockedOnMonitorEnterState` is supporting just HotSpot  `JavaThread`'s and so, it is changing the carrier thread state only.
>> 
>> The fix is to move the definition of the `JavaThreadBlockedOnMonitorEnterState` object after block where `try_preempt()` is called.
>> 
>> Testing:
>>  - Checked the failed test does not fail with the fix: `serviceability/jvmti/vthread/StopThreadTest/StopThreadTest.java`
>>  - Ran mach5 tiers 1-6
>
> Serguei Spitsyn has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review: preserve platform thread behavior

src/hotspot/share/runtime/objectMonitor.hpp line 393:

> 391:   bool      try_enter(JavaThread* current, bool check_for_recursion = true);
> 392:   bool      spin_enter(JavaThread* current);
> 393:   void      notify_contended_enter(JavaThread *current);

This helper method should be private. Thanks

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PR Review Comment: https://git.openjdk.org/jdk/pull/23125#discussion_r1919629750