RFR: 8360046: Scalability issue when submitting virtual threads with almost empty tasks [v23]

[Viktor Klang]

On Sun, 30 Nov 2025 17:51:45 GMT, Doug Lea <dl at openjdk.org> wrote:

>> This set of updates reduces contention-based performance loss under heavy over-subscription, while also improving perfomance more generally.
>
> Doug Lea 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 35 additional commits since the last revision:
> 
>  - Merge branch 'openjdk:master' into JDK-8360046
>  - Cleanup
>  - For testing
>  - Merge branch 'openjdk:master' into JDK-8360046
>  - restore positioning of threadlocal clears
>  - Add comment
>  - Merge branch 'openjdk:master' into JDK-8360046
>  - Signal on setParallelism
>  - Drop added Contended region; simplify accordingly
>  - Tweaks
>  - ... and 25 more: https://git.openjdk.org/jdk/compare/05c38cfc...654c1dc6

Thanks for all your work here, @DougLea!

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Marked as reviewed by vklang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26479#pullrequestreview-3529497943