[jdk17u-dev] RFR: 8306738: Select num workers for safepoint ParallelCleanupTask

[Paul Hohensee]

On Fri, 19 May 2023 14:54:41 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Unclean backport to considerably improve the safepoint cleanup times. The backport is not clean, because the `WorkGang` -> `WorkerThreads` rename is missing. The is also the addition of `Dictionary::does_any_dictionary_needs_resizing` check, because JDK 17 is still have that resize code in JDK 17.
> 
> Additional testing:
>  - [x] Ad-hoc benchmarks
>  - [ ] Linux x86_64 fastdebug `tier1 tier2 tier3`
> 
> The experiments (see original PR) show we win big on this:
> ![plot](https://github.com/openjdk/jdk17u-dev/assets/1858943/fd69b925-fa69-4e13-ac8c-e0dd72dd43cd)

Lgtm.

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Marked as reviewed by phh (Reviewer).

PR Review: https://git.openjdk.org/jdk17u-dev/pull/1379#pullrequestreview-1434656013