RFR: 8296768: Use different explicit claim marks for CLDs in Parallel and Serial GC

[Thomas Schatzl]

On Thu, 10 Nov 2022 19:52:45 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   please review this change that implements the same optimization as [JDK-8295871](https://bugs.openjdk.org/browse/JDK-8295871) to use different claim marks for different full gc phases for Parallel and Serial GC. For both collectors I decided to clear all marks before full gc, but that is arbitrary. If you want this could be done at the end to the same effect.
> 
> Testing: tier1-5 (with JDK-8295871)
> 
> Thanks,
>   Thomas

I moved the CLD claim to the end of GC after all for both gcs - this minimizes the total work for clearing (i.e. put it right after purging the dead CLDs).
Another tier1-5 run almost completed.

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PR: https://git.openjdk.org/jdk/pull/11092