RFR: 8369420: Parallel: Using multiple workers for class unloading [v2]

[Thomas Schatzl]

On Wed, 8 Oct 2025 13:05:15 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Support parallel class unloading in ParallelGC. Much inspiration taken from `G1ParallelCleaningTask`.
>> 
>> Test: tier1-5
>
> Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review

Marked as reviewed by tschatzl (Reviewer).

src/hotspot/share/gc/parallel/psParallelCompact.cpp line 1177:

> 1175:       // Serial work; only first worker.
> 1176:       // Clean JVMCI metadata handles.
> 1177:       JVMCI_ONLY(JVMCI::do_unloading(_unloading_occurred));

Potentially do not execute this if `EnableJVMCI` is false. Probably does not change a lot.

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PR Review: https://git.openjdk.org/jdk/pull/27689#pullrequestreview-3315000652
PR Review Comment: https://git.openjdk.org/jdk/pull/27689#discussion_r2413988771