8369178: G1: Use NMethodMarkingScope and ThreadsClaimTokenScope in G1RootProcessor

[fandreuz]

Replace StrongRootsScope with ThreadsClaimTokenScope and MarkingNMethodClosure in G1RootProcessor to be more precise with what is needed and why.

• MarkingNMethodClosure is used in G1FullGCMarkTask, so we also need NMethodMarkingScope.
• active_workers is guaranteed to be > 0

Passes tier1 and tier2 (fastdebug).

---

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Issue

• JDK-8369178: G1: Use NMethodMarkingScope and ThreadsClaimTokenScope in G1RootProcessor (Enhancement - P4)

Reviewers

• Albert Mingkun Yang (@albertnetymk - Reviewer)

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8369178: G1: Use NMethodMarkingScope and ThreadsClaimTokenScope in G1RootProcessor

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At the time when this comment was updated there had been 3 new commits pushed to the master branch:

• e3320a9: 8367610: Test tools/sincechecker/modules/java.base/JavaBaseCheckSince.java timed out on Windows
• 2bfada3: 8364927: Add @requires annotation to TestReclaimStringsLeaksMemory.java
• 2c114d6: 8367899: compiler/c2/gvn/TestBitCompressValueTransform.java intermittent timed out

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[albertnetymk]

I would have used uint _num_workers, but I guess this also works.

[fandreuz]

We don't need to know how many workers there are, just if we are parallel or not. I think this goes in the same direction as the idea of the PR, being clear about what we actually need

[albertnetymk]

/cc hotspot-gc

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The hotspot-gc label was successfully added.