RFR: 8369068: GenShen: Generations still aren't reconciled assertion failure [v2]

[William Kemper]

On Fri, 17 Oct 2025 22:58:20 GMT, Y. Srinivas Ramakrishna <ysr 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 nine commits:
>> 
>>  - Merge remote-tracking branch 'jdk/master' into reduce-gc_generation-usage
>>  - Merge remote-tracking branch 'jdk/master' into reduce-gc_generation-usage
>>  - Remove _gc_generation from ShenandoahHeap
>>  - Little cleanup, remove one active generation usage
>>  - Merge remote-tracking branch 'jdk/master' into reduce-gc_generation-usage
>>  - Finish removing usages of gc_generation, start on reducing usages of active_generation
>>  - Fix build
>>  - Use existing _generation field instead of Heap::_gc_generation where possible
>>  - Only shenandoah vm operations participate in active/gc generation scheme
>
> @earthling-amzn : is it possible to add the stack retrace and the test that elicited the assertion failure to the ticket as an archival forensic trail?

@ysramakrishna - Aye, the original, linked ticket has the stack traces and logs: https://bugs.openjdk.org/browse/JDK-8365792. Also a description of our original understanding of the problem in this PR: https://github.com/openjdk/jdk/pull/27373. That understanding is still valid, it's just that `ShenandoahSafepoint::is_at_shenandoah_safepoint` lies when it is called from a concurrent worker thread.

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PR Comment: https://git.openjdk.org/jdk/pull/27703#issuecomment-3417557209