RFR: 8337511: Implement JEP 404: Generational Shenandoah (Experimental) [v5]

[Roman Kennke]

On Mon, 21 Oct 2024 21:16:50 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> This PR merges JEP 404, a generational mode for the Shenandoah garbage collector. The JEP can be viewed here: https://openjdk.org/jeps/404. We would like to target JDK24 with this PR.
>
> William Kemper has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 492 commits:
> 
>  - Merge remote-tracking branch 'shenandoah/master' into great-genshen-pr-redux
>  - Merge
>  - 8342560: GenShen: Fix confusing method name
>    
>    Reviewed-by: ysr
>  - 8342564: GenShen: Only reference young/old generation names in generational mode
>    
>    Reviewed-by: xpeng, ysr
>  - Merge remote-tracking branch 'jdk/master' into great-genshen-pr-redux
>  - Merge remote-tracking branch 'shenandoah/master' into great-genshen-pr-redux
>  - 8342214: GenShen: Reduce code duplication in shFreeSet with iterator abstraction
>    
>    Reviewed-by: kdnilsen, ysr
>  - 8342239: GenShen: Revert changes in adaptive heuristic to avoid overflow on 32 bit
>    
>    Reviewed-by: ysr
>  - 8342278: GenShen: Move non-generational mode test out of generational test configuration
>    
>    Reviewed-by: ysr
>  - 8342255: GenShen: Remove unnecessary enum initial values
>    
>    Reviewed-by: ysr
>  - ... and 482 more: https://git.openjdk.org/jdk/compare/71583222...2a2aa408

I've looked at the changes again, especially at all that changed since my last full review. It's looking good to me, now. Please remove the one newline that I've spotted. Thanks for this work, this is really a huge effort!

src/hotspot/share/gc/shenandoah/shenandoahFreeSet.hpp line 1:

> 1: 

This newline is one too much.

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

Marked as reviewed by rkennke (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/21273#pullrequestreview-2388573425
PR Review Comment: https://git.openjdk.org/jdk/pull/21273#discussion_r1812694226