RFR: 8284632: runtime/Thread/StopAtExit.java possibly leaking memory again

[Daniel D.Daugherty]

On Wed, 27 Apr 2022 22:04:17 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> The target thread sets the `_terminated` field to `_thread_exiting` in
>> src/hotspot/share/runtime/thread.cpp: JavaThread::exit() AFTER the
>> creation of the `NoAsyncExceptionDeliveryMark` object that protects
>> the VM call out to `Thread::exit()`. The dcubed_async_blocked_cnt
>> counter I mumble about above is counted before the target thread
>> sets the `_terminated` field to `_thread_exiting` so that's why adding
>> the new `is_exiting()` check is so ineffective.
>
> I don't understand, was the clean_async_exception_operation() call in JavaThread::exit() removed? The only place where another async exception could have been installed after the call to clean_async_exception_operation()(if not removed) and the change of state to _thread_exiting is in post_thread_end(). So if anything we would need to call it after that. Is your testing calling that jvmti event?

Sorry for confusing you. I probably shouldn't be mumbling about my debugging
here in the PR. Please ignore the debugging comments above.

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PR: https://git.openjdk.java.net/jdk/pull/8388