RFR: 8288139: JavaThread touches oop after GC barrier is detached

[Daniel D.Daugherty]

On Wed, 15 Jun 2022 18:51:05 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> Update SharedRuntime::get_java_tid() to verify that the calling thread is safely
>> accessing its own threadObj(). This check uses the new is_gc_barrier_detached()
>> function added by [JDK-8288497](https://bugs.openjdk.org/browse/JDK-8288497) add support for JavaThread::is_gc_barrier_detached().
>> 
>> The above check was used to reproduce the failure mode without Shenandoah
>> and the remainder of the fix relocates the offending code from
>> ThreadsSMRSupport::remove_thread() to Threads::remove(). The work of
>> removed the 'tid' entry from the ThreadIdTable is still done under the
>> protection of the Threads_lock.
>> 
>> This fix along with the fix for JDK-8288497 has been tested in Mach5 Tier[1-8].
>> There are no related failures in Mach5 Tier[1-7]; Mach5 Tier8 is still running.
>
> Looks good to me! I only have one comment but made it in 8288497 because it applies more to that change.
> 
> Thanks,
> Patricio

@pchilano - Thanks for the review!

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PR: https://git.openjdk.org/jdk19/pull/21