RFR: 8343840: Rewrite the ObjectMonitor lists [v2]

[Coleen Phillimore]

On Mon, 3 Mar 2025 23:18:13 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> Fredrik Bredberg has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update after review by David and Coleen.
>
> src/hotspot/share/runtime/objectMonitor.cpp line 1359:
> 
>> 1357:     // Build the doubly linked list to get hold of currentNode->prev().
>> 1358:     _entry_list_tail = nullptr;
>> 1359:     entry_list_tail(current);
> 
> I think we should try to avoid having to rebuild the doubly link list from scratch, since only a few nodes in the front might be missing the previous links. For platform threads it might not matter that much, but for virtual threads this list could be much larger. Maybe we can leave it as a future enhancement.

We don't have a prev node, we don't know which node to set next to our next node to.  The list will be broken.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23421#discussion_r1979432912