RFR: 8368599: ShenandoahConcurrentMark could use ThreadsClaimTokenScope [v2]

[Albert Mingkun Yang]

On Thu, 25 Sep 2025 14:16:43 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> So, what calls nmethod::oops_do_marking_prologue/epilogue, and do we know it is (not) needed?

`nmethod::oops_do_marking_prologue/epilogue` is meant to undo the effect of `oops_do_try_claim` in `MarkingNMethodClosure`. Since Shenandoah conc marking doesn't use `MarkingNMethodClosure`, it's not needed. (STW full-gc marking, `ShenandoahSTWMark`, uses `MarkingNMethodClosure` though.)

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PR Comment: https://git.openjdk.org/jdk/pull/27477#issuecomment-3334488740