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

[William Kemper]

On Fri, 11 Oct 2024 13:43:46 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
>
> test/hotspot/jtreg/gc/shenandoah/TestAllocIntArrays.java line 100:
> 
>> 98: 
>> 99: /*
>> 100:  * @test id=generational
> 
> You are making a test configuration and call it 'generational' but then one of the two run configurations doesn't actually run with generational mode. You probably want to separate the two?

https://bugs.openjdk.org/browse/JDK-8342278

> test/hotspot/jtreg/gc/shenandoah/TestAllocIntArrays.java line 163:
> 
>> 161:         final int min = 0;
>> 162:         final int max = 384 * 1024;
>> 163:         // Each allocated int array is assumed to consume 16 bytes for alignment and header, plus
> 
> With the upcoming 'compact headers' it's going to be only 12 bytes. If that matters, then the actual number should perhaps be a constant? Preexisting and not relevant for this PR, though.

Yes, not sure that level of precision is really required for this test either.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21273#discussion_r1802109516
PR Review Comment: https://git.openjdk.org/jdk/pull/21273#discussion_r1802109841