8365571: GenShen: PLAB promotions may remain disabled for evacuation threads

[earthling-amzn]

Clean backport. Fixes performance issue with generational mode for Shenandoah.

---

Progress

• JDK-8365571 needs maintainer approval
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8365571: GenShen: PLAB promotions may remain disabled for evacuation threads (Bug - P4 - Approved)

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[bridgekeeper]

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[openjdk]

@earthling-amzn This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8365571: GenShen: PLAB promotions may remain disabled for evacuation threads

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At the time when this comment was updated there had been 20 new commits pushed to the master branch:

• c4f45dd: 8279005: sun/tools/jstat tests do not check for test case exit codes after JDK-8245129
• 1a0507d: 8362169: Pointer passed to upcall may get wrong scope
• f1d867d: 8364996: java/awt/font/FontNames/LocaleFamilyNames.java times out on Windows
• ... and 17 more: https://git.openjdk.org/jdk25u/compare/dd748358b88c2a715fcf0e01ed66b77551616d85...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @earthling-amzn This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 00: Full (a9be3d15)

[earthling-amzn]

/approval request This change addresses a performance issue in the generational mode of Shenandoah which may cause evacuating threads to be stuck in a state where they are unable to perform promotions. This change only touches Shenandoah code. We have tested it with GHA, and jtreg all (with Shenandoah and again with Shenandoah's generational mode) and also Dacapo, Extremem, SpecJVM2008, SpecJBB2015, Renaissance, and Heapothesys.

[openjdk]

@earthling-amzn
8365571: The approval request has been created successfully.

[earthling-amzn]

/integrate

[openjdk]

@earthling-amzn
Your change (at version a9be3d1) is now ready to be sponsored by a Committer.

[shipilev]

/sponsor

[openjdk]

Going to push as commit ff97b1f.
Since your change was applied there have been 25 commits pushed to the master branch:

• a7b977c: 8362207: Add more test cases for possible double-rounding in fma
• 5fc2f1b: 8365468: EagerJVMCI should only apply to the CompilerBroker JVMCI runtime
• 6b3a2fd: 8364503: gc/g1/TestCodeCacheUnloadDuringConcCycle.java fails because of race printing to stdout
• ... and 22 more: https://git.openjdk.org/jdk25u/compare/dd748358b88c2a715fcf0e01ed66b77551616d85...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev @earthling-amzn Pushed as commit ff97b1f.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.