RFR: 8337511: Implement JEP 404: Generational Shenandoah (Experimental) [v7]

[William Kemper]

On Tue, 19 Nov 2024 16:46:36 GMT, Aleksey Shipilev <shade 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 510 commits:
>> 
>>  - Merge branch 'merge-latest' into great-genshen-pr-redux
>>  - Use new CompactHeader forwarding APIs in generational mode
>>  - Merge remote-tracking branch 'jdk/master' into merge-latest
>>  - Merge
>>  - 8343649: Shenandoah: ShenandoahEvacInfo event does not follow JFR guidelines
>>    
>>    Reviewed-by: wkemper
>>  - Merge
>>  - 8343227: GenShen: Fold resource mark into management of preselected regions
>>    
>>    Reviewed-by: kdnilsen
>>  - Merge openjdk/jdk tip into great-genshen-pr-redux
>>  - Merge remote-tracking branch 'jdk/master' into merge-latest
>>  - Merge remote-tracking branch 'jdk/master' into merge-latest
>>  - ... and 500 more: https://git.openjdk.org/jdk/compare/889f9062...5e02b5d8
>
> src/hotspot/share/gc/shenandoah/shenandoahVerifier.cpp line 657:
> 
>> 655:           _generation(nullptr) {
>> 656:     if (_options._verify_marked == ShenandoahVerifier::_verify_marked_complete_satb_empty) {
>> 657:       Threads::change_thread_claim_token();
> 
> It is fairly odd to see Verifier touching the claim token, since the bug _may be_ somewhere in parallel thread oop iteration infra. I think it is fine to just use `Threads::threads_do` (non-parallel version), which AFAIU does not require token modifications.

Will test this.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21273#discussion_r1849329578