RFR: 8298377: JfrVframeStream causes deadlocks in ZGC [v2]

[Stefan Karlsson]

On Wed, 18 Jan 2023 15:03:34 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> src/hotspot/share/jfr/periodic/sampling/jfrThreadSampler.cpp line 393:
>> 
>>> 391:   // stack walk over Loom continuations. The stack walking code will otherwise
>>> 392:   // skip frames in stack chunks on the Java heap.
>>> 393:   StackWatermarkSet::start_processing(thread, StackWatermarkKind::gc);
>> 
>> Maybe this should be moved to under each thread_state_in_java() and thread_state_in_native() preliminary check, see below. That way we only call on threads that we will eventually attempt to suspend.
>
> Just stick it into each of JfrThreadSampleClosure::sample_thread_in_java() and JfrThreadSampleClosure::sample_thread_in_native() member functions,

Pushed a commit. Could you check it?

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PR: https://git.openjdk.org/jdk/pull/11586