RFR: 8334445: Parallel: Decouple maximum compaction from SoftReference clearing [v3]

[Albert Mingkun Yang]

On Fri, 5 Jul 2024 09:54:26 GMT, Liang Mao <lmao at openjdk.org> wrote:

>> Albert Mingkun Yang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
>> 
>>  - Merge branch 'master' into pgc-max-compact
>>  - Merge branch 'master' into pgc-max-compact
>>  - pgc-max-compact
>
> src/hotspot/share/gc/parallel/psParallelCompact.hpp line 741:
> 
>> 739:   static void fill_dense_prefix_end(SpaceId id);
>> 740: 
>> 741:   static void summary_phase();
> 
> After this change, will the clear-soft-refs full gc become non-maximum from maximum compact and affect the current behavior?

After the change, clear-soft-refs and max-compaction (not leaving any deadwood) will be two independent decisions, which can result into externally visible change-of-behavior, e.g. shorter full-gc in certain cases, since max-compaction is trading time for space.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/19763#discussion_r1668219424