Integrated: 8280396: G1: Full gc mark stack draining should prefer to make work available to other threads

[Thomas Schatzl]

On Fri, 21 Jan 2022 14:33:46 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   can I have reviews for this change that fixes a significant performance problem with g1 full gc marking when the overflow queue is in use? Basically this case causes the threads never share their work from the overflow queue, resulting in very bad parallelization in some cases.
> 
> This is a problem that has been fixed already in [JDK-8152438](https://bugs.openjdk.java.net/browse/JDK-8152438), but when looking at this code on g1 and parallel full gc, they both showed that issue.
> 
> This is the change for g1.
> 
> The CR shows some numbers how bad this can be.
> 
> Thanks,
>   Thomas

This pull request has now been integrated.

Changeset: 674a97b2
Author:    Thomas Schatzl <tschatzl at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/674a97b27ef621e7b54c13c121c625f91df5ee60
Stats:     50 lines in 2 files changed: 32 ins; 10 del; 8 mod

8280396: G1: Full gc mark stack draining should prefer to make work available to other threads

Reviewed-by: sjohanss, ayang

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PR: https://git.openjdk.java.net/jdk/pull/7175