RFR: 8311177: Switching to interpreter only mode in carrier thread can lead to crashes [v2]

[Serguei Spitsyn]

On Wed, 29 May 2024 19:06:57 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: addressed nits in new test
>
> test/hotspot/jtreg/serviceability/jvmti/vthread/MethodExitTest/libMethodExitTest.cpp line 201:
> 
>> 199: 
>> 200:   // need to reset this value after the breakpoint_hit1
>> 201:   received_method_exit_event = JNI_FALSE;
> 
> There was a loom-dev email thread regarding this last year. Seems related. I had concluded that the way the test was written that no MethodExit event should have been received. I'm not sure if I missed something in my analysis or if this failure is a result of your changes:
> 
> https://mail.openjdk.org/pipermail/loom-dev/2023-August/006059.html
> https://mail.openjdk.org/pipermail/loom-dev/2023-September/006170.html

Thank you for the comment and links to the discussion. In fact, I've observed the MethodExit events really posted between the breakpoint hits: `hit1` and `hit2`. The first one is at the return from the `unmount()` method. I was not able to prove why they should not be expected.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19438#discussion_r1619756552