RFR: 8322732: ForkJoinPool may underutilize cores in async mode

[Viktor Klang]

On Tue, 7 May 2024 22:50:18 GMT, Doug Lea <dl at openjdk.org> wrote:

> This set of changes address causes of poor utilization with small numbers of cores due to overly aggressive contention avoidance. A number of further adjustments were needed to still avoid most contention effects in deployments with large numbers of cores

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 1830:

> 1828:             phase = w.phase;
> 1829:             if ((src = w.source) != DROPPED) {
> 1830:                 w.source = DROPPED;        // else already dropped

@DougLea Would there be any gain in atomically swapping out `w.source` to `DROPPED`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/19131#discussion_r1596425162