RFR: 8360046: Scalability issue when submitting virtual threads with almost empty tasks [v5]

[Viktor Klang]

On Thu, 7 Aug 2025 14:03:40 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 incrementally with one additional commit since the last revision:
> 
>   Avoid underutilization on resize

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 2072:

> 2070:                     p = awaitWork(w, p);      // block, drop, or exit
> 2071:             }
> 2072:         }

@DougLea if `w != null` is always expected to be `true`, it might make sense to throw some form of exception in case it actually is. Possibly an assertion?

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PR Review Comment: https://git.openjdk.org/jdk/pull/26479#discussion_r2276387045