RFR: 8336707: Contention of ForkJoinPool grows when stealing works [v29]

[Alan Bateman]

On Tue, 19 Nov 2024 16:57:05 GMT, Viktor Klang <vklang at openjdk.org> wrote:

>> Doug Lea has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Ensure InnocuousForkJoinWorkerThread usable with or without SecurityManager
>
> src/java.base/share/classes/java/util/concurrent/ForkJoinWorkerThread.java line 247:
> 
>> 245:         = U.objectFieldOffset(Thread.class, "threadLocals");
>> 246:     private static final long INHERITABLETHREADLOCALS
>> 247:         = U.objectFieldOffset(Thread.class, "inheritableThreadLocals");
> 
> @AlanBateman Thoughts here? 🤔

resetThreadLocals looks good although. A discussion point is whether it the reset should be done for all FJP instances, not just the common pool but not this PR.

> src/java.base/share/classes/java/util/concurrent/ForkJoinWorkerThread.java line 270:
> 
>> 268:         @SuppressWarnings("removal")
>> 269:         public void setContextClassLoader(ClassLoader cl) {
>> 270:             if (System.getSecurityManager() != null &&
> 
> @AlanBateman Alternatives for this? 🤔

I don't think it needs an alternative, instead L270-272 will be removed as part of the SM cleanup.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21507#discussion_r1849809984
PR Review Comment: https://git.openjdk.org/jdk/pull/21507#discussion_r1849810047