Integrated: 8265842: G1: Introduce API to run multiple separate tasks in a single gangtask

[Thomas Schatzl]

On Fri, 23 Apr 2021 11:54:49 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> [JDK-8214237](https://bugs.openjdk.java.net/browse/JDK-8214237) is going to join different somewhat independent (sub-)tasks of the post evacuation phase into basically two gangtasks to improve performance (reduce startup and shutdown of work gangs).
> 
> To facilitate doing that, introduce an API that manages subtasks of a given gangtask and provide some helpers to do common work.
> 
> This CR is only about adding the API and testing to somewhat simplify the actual move of the post evacuate tasks into parallel tasks. There is no new functionality here, only to split up [JDK-8214237](https://bugs.openjdk.java.net/browse/JDK-8214237) a bit.
> 
> [Here](https://github.com/openjdk/jdk/compare/master...tschatzl:parallel-phases-join-everything) is the full change that uses this API to implement JDK-8214237 (which I'll try to split up a bit before) to see how it will be used (in [G1YoungGCPostEvacuateTasks.hpp](https://github.com/openjdk/jdk/commit/1d8667143e7d106b96c25c0b876c37f1250be132#diff-64bc43a24e11978920bb9523cb1507a7275ace22d9eead4c34177339a3258e42) ).
> 
> Testing: new gtest, tier1-5 with mentioned patch for JDK-8214237.
> 
> Thanks,
> Thomas

This pull request has now been integrated.

Changeset: c76ce287
Author:    Thomas Schatzl <tschatzl at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/c76ce28754658135a544dbfc6b8f767a4185842e
Stats:     415 lines in 3 files changed: 415 ins; 0 del; 0 mod

8265842: G1: Introduce API to run multiple separate tasks in a single gangtask

Reviewed-by: lkorinth, ayang, sjohanss, iwalulya

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PR: https://git.openjdk.java.net/jdk/pull/3653