RFR: 8319137: release _object in ObjectMonitor dtor to avoid races [v3]

[Stefan Karlsson]

On Mon, 20 Nov 2023 17:37:15 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> Please review the following fix which moves the release of the _object WeakHandle back to the ObjectMonitor dtor. Releasing it earlier as we do today introduces a race which can lead to crashes. Tested running tiers123 in mach5.
>> 
>> This fix is an effective backout of [JDK-8256302](https://bugs.openjdk.org/browse/JDK-8256302).
>> 
>> Thanks,
>> Patricio
>
> Patricio Chilano Mateo has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove redundant branches

Marked as reviewed by stefank (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/16738#pullrequestreview-1740414840