[jdk17u-dev] Integrated: 8227060: Optimize safepoint cleanup subtask order

[Aleksey Shipilev]

On Fri, 19 May 2023 13:36:08 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Unclean backport to improve the safepoint cleanup times. Provides the grounds for the ultimate improvement in safepoint cleanup ([JDK-8306738](https://bugs.openjdk.org/browse/JDK-8306738)). The backport is not clean, because there are copyright years conflicts, the rename of `AbstractGangTask` to `WorkerTask` is missing, `WorkGang` -> `WorkerThreads` rename is missing, `JavaThread::cast` cleanup is missing.
> 
> Additional testing:
>  - [x] Ad-hoc benchmarks
>  - [x] Linux x86_64 fastdebug `tier1 tier2 tier3`
> 
> The safepoint cleanup times are slightly better on small tests, and there seem to be no regressions.
> ![plot](https://github.com/openjdk/jdk17u-dev/assets/1858943/7e012482-71f8-459f-aca0-4c043b791e92)

This pull request has now been integrated.

Changeset: 464a32b0
Author:    Aleksey Shipilev <shade at openjdk.org>
URL:       https://git.openjdk.org/jdk17u-dev/commit/464a32b0ee50972d93a1df5bfcac5c87052d8ef7
Stats:     60 lines in 5 files changed: 20 ins; 34 del; 6 mod

8227060: Optimize safepoint cleanup subtask order

Reviewed-by: phh
Backport-of: 96a542feb2064dba155ebf05311752995d164038

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PR: https://git.openjdk.org/jdk17u-dev/pull/1377