RFR: 8340698: JVMTI FRAME_POP event is sometimes missed if NotifyFramePop is called as a method is returning [v8]

[Chris Plummer]

On Fri, 18 Oct 2024 00:28:51 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> There is a race between JVMTI NotifyFramePop function and FramePop event posting code.
>> The fix is to return JVMTI_ERROR_OPAQUE_FRAME if if a FramePop event with depth 0 is requested by NotifyFramePop at the time when the target frame is in exit epilogue, and MethodExit/FramePop events are being posted for it.
>> 
>> Testing:
>>  - verified locally with new test (developed by Chris): `serviceability/jvmti/events/NotifyFramePopStressTest`
>>  - TBD: mach5 tiers 1-6
>
> Serguei Spitsyn has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review: move pop_count++ to the end of FramePop handler for more safety

test/hotspot/jtreg/serviceability/jvmti/events/NotifyFramePopStressTest/libNotifyFramePopStressTest.cpp line 73:

> 71: 
> 72:   name = get_method_name(jvmti, jni, method);
> 73:   LOG("FramePop(%d) event from method: %s %s\n", pop_count, csig, name);

I just noticed this pop_count reference here. Probably best to change it to pop_count  + 1.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21468#discussion_r1805661610