RFR: 8330969: scalability issue with loaded JVMTI agent [v2]

[Serguei Spitsyn]

On Fri, 26 Apr 2024 19:38:40 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> Serguei Spitsyn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   review: fixed minor issues: renamed function, corrected comment, removed typo in assert
>
> src/hotspot/share/prims/jvmtiThreadState.cpp line 433:
> 
>> 431:   // Avoid using MonitorLocker on performance critical path, use
>> 432:   // two-level synchronization with lock-free operations on counters.
>> 433:   assert(!thread->VTMS_transition_mark(), "sanity check");
> 
> The "counters" comment needs to be updated.

Nice catch, thanks. Fixed now.

> src/hotspot/share/prims/jvmtiThreadState.cpp line 456:
> 
>> 454:     // Slow path: undo unsuccessful optimistic counter incrementation.
>> 455:     // It can cause an extra waiting cycle for VTMS transition disablers.
>> 456:     thread->set_VTMS_transition_mark(false);
> 
> The "optimistic counter incrementation" comment needs updating.

Nice catch, thanks. Fixed now.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18937#discussion_r1584018624
PR Review Comment: https://git.openjdk.org/jdk/pull/18937#discussion_r1584018405