RFR: 8328366: Thread.setContextClassloader from thread in FJP commonPool task no longer works after JDK-8327501

[Mandy Chung]

On Tue, 19 Mar 2024 12:16:29 GMT, Viktor Klang <vklang at openjdk.org> wrote:

> This is a draft PR with a potential solution to 8328366 without regressing 8327501.
> 
> @DougLea To avoid regressions in the future, where would regression tests for this ideally be located?

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 1143:

> 1141:             @SuppressWarnings("removal")
> 1142:             SecurityManager sm = System.getSecurityManager();
> 1143:             if (sm != null && isCommon)

For common thread pool, if SM is not enabled, it will create `ForkJoinWorkerThread` that does not clear thread locals which is different than JDK 18 behavior.  Is this intentional?

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PR Review Comment: https://git.openjdk.org/jdk/pull/18374#discussion_r1532497712