RFR: 8337511: Implement JEP-404: Generational Shenandoah (Experimental) [v3]

[Roman Kennke]

On Thu, 10 Oct 2024 13:13:14 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> William Kemper has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 478 commits:
>> 
>>  - Fix merge error
>>  - Merge remote-tracking branch 'jdk/master' into great-genshen-pr-redux
>>  - Merge remote-tracking branch 'jdk/master' into great-genshen-pr-redux
>>  - Merge branch 'shenandoah/master' into great-genshen-pr-redux
>>  - Merge
>>  - 8341099: GenShen: assert(HAS_FWD == _heap->has_forwarded_objects()) failed: Forwarded object status is sane
>>    
>>    Reviewed-by: kdnilsen
>>  - 8341485: GenShen: Make evac tracker a non-product feature and confine it to generational mode
>>    
>>    Reviewed-by: kdnilsen, ysr
>>  - Merge
>>  - 8341042: GenShen: Reset mark bitmaps for unaffiliated regions when preparing for a cycle
>>    
>>    Reviewed-by: kdnilsen
>>  - 8339616: GenShen: Introduce new state to distinguish promote-in-place phase as distinct from concurrent evacuation
>>    
>>    Reviewed-by: kdnilsen, shade, ysr
>>  - ... and 468 more: https://git.openjdk.org/jdk/compare/b9db74a6...4db1e0e1
>
> src/hotspot/share/gc/shenandoah/heuristics/shenandoahHeuristics.hpp line 79:
> 
>> 77: 
>> 78: protected:
>> 79:   static const uint Moving_Average_Samples = 10; // Number of samples to store in moving averages
> 
> I've never seen that style for constants in HotSpot before. I'd either make it MOVING_AVERAGE_SAMPLES or MovingAverageSamples. I think the latter is more prevalent, but I am not certain.

Oh but I see that it's used in this source file. Hmm... So maybe stick with it for now and make a follow-up change?

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PR Review Comment: https://git.openjdk.org/jdk/pull/21273#discussion_r1795404177