RFR: 8343840: Rewrite the ObjectMonitor lists [v2]

[Patricio Chilano Mateo]

On Tue, 4 Mar 2025 13:27:17 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> 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.

Right, we still have to set the previous links for those nodes. I'm just suggesting we don't have to walk the whole list, just until the last node we set the previous pointer.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23421#discussion_r1979963352