RFR: 8338977: Parallel: Improve heap resizing heuristics [v22]

[Albert Mingkun Yang]

On Fri, 12 Dec 2025 09:37:48 GMT, SilenceZheng66 <duke 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 pull request now contains 33 commits:
>> 
>>  - merge
>>  - Merge branch 'master' into pgc-size-policy
>>  - review
>>  - review
>>  - Merge branch 'master' into pgc-size-policy
>>  - review
>>  - review
>>  - Merge branch 'master' into pgc-size-policy
>>  - Merge branch 'master' into pgc-size-policy
>>  - review
>>  - ... and 23 more: https://git.openjdk.org/jdk/compare/7da274de...295dc853
>
> src/hotspot/share/gc/parallel/psParallelCompact.cpp line 1070:
> 
>> 1068:     size_policy->sample_old_gen_used_bytes(MAX2(pre_gc_values.old_gen_used(), old_gen->used_in_bytes()));
>> 1069: 
>> 1070:     if (UseAdaptiveSizePolicy) {
> 
> I think this code block could raise heap size don't expand in some specific case, maybe you should optimize it. @albertnetymk

@SilenceZheng66 Could you elaborate the issue, ideally, in a JBS ticket? (A reproducer/gc-log would be nice, but detailed description works as well.)

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PR Review Comment: https://git.openjdk.org/jdk/pull/25000#discussion_r2615984879