RFR: 8322732: ForkJoinPool may underutilize cores in async mode [v17]

[Viktor Klang]

On Fri, 31 May 2024 13:18:33 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
>
> Doug Lea has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Reconcile changes

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 1345:

> 1343:             int b = base, p = top, cap;
> 1344:             if (p - b > 0 && a != null && (cap = a.length) > 0) {
> 1345:                 for (int m = cap - 1, s, nb;;) {

@DougLea I'm curious, what effect did you see if moving the `p - b > 0` out of the loop conditional?

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PR Review Comment: https://git.openjdk.org/jdk/pull/19131#discussion_r1623453077