RFR: 8256302: releasing oopStorage when deflating allows for faster deleting [v3]

[Daniel D. Daugherty]

On Mon, 22 May 2023 20:02:21 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> Releasing ObjectMonitor oopStorage earlier when deflating allows ObjectMonitor
>> deletion by a JavaThread (usually the MonitorDeflationThread) to happen while a
>> ThreadBlockInVM helper is in place. This should improve time-to-safepoint.
>
> Daniel D. Daugherty has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:
> 
>  - Merge tag 'jdk-21+23' into JDK-8256302
>    
>    Added tag jdk-21+23 for changeset 6d4782bc
>  - address the easy dholmes and kimbarrett CR comments
>  - 8256302: releasing oopStorage when deflating allows for faster deleting

Sigh... when the _object WeakHandle is released, the `release()` function does
not clear the `WeakHandle::_obj` field so we have a "dangling" `_obj` field which
is why `_object.is_null()` returns false even though the `_object` has been released.

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PR Comment: https://git.openjdk.org/jdk/pull/11296#issuecomment-1572762066