RFR: 8256302: releasing oopStorage when deflating allows for faster deleting [v5]

[Coleen Phillimore]

On Tue, 29 Nov 2022 21:21:15 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> Daniel D. Daugherty has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
>> 
>>  - Merge tag 'jdk-21+25' into JDK-8256302
>>    
>>    Added tag jdk-21+25 for changeset a46b5acc
>>  - Allow ObjectMonitor::_object to be reset to nullptr when it is released which allows the code to be cleaner.
>>  - 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
>
> src/hotspot/share/runtime/objectMonitor.cpp line 598:
> 
>> 596: 
>> 597:   // Release object's oop storage since the ObjectMonitor has been deflated:
>> 598:   release_object();
> 
> Just to be clear, deflate_monitor() is called when a JavaThread is
> in VM (or by the VM Thread) so it is safe to call release.

I hope OopStorage.release() will assert if it's not safe.  I think it does.

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PR Review Comment: https://git.openjdk.org/jdk/pull/11296#discussion_r1220237863