8318986: Improve GenericWaitBarrier performance

[shipilev]

Clean backport to drastically improve safepoint performance under heavy load, fixing regression between JDK 11 and JDK 17.

Additional testing:

• Ad-hoc performance runs, expected improvements
• MacOS AArch64 server fastdebug, all tests

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8318986 needs maintainer approval

Issue

• JDK-8318986: Improve GenericWaitBarrier performance (Enhancement - P3 - Approved)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk21u-dev.git pull/70/head:pull/70
$ git checkout pull/70

Update a local copy of the PR:
$ git checkout pull/70
$ git pull https://git.openjdk.org/jdk21u-dev.git pull/70/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 70

View PR using the GUI difftool:
$ git pr show -t 70

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21u-dev/pull/70.diff

Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back shade! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

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

[openjdk]

⚠️ @shipilev 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

• 04: Full - Incremental (6e60ef45)
• 03: Full - Incremental (17d9b6e6)
• 02: Full - Incremental (2aada3b9)
• 01: Full - Incremental (98149cc1)
• 00: Full (3e336a13)

[openjdk]

@shipilev Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

[shipilev]

GHA failure in RISC-V build is infrastructural: JDK-8326960.

[shipilev]

/approval request Clean backport to drastically improve safepoint performance under heavy load, fixing regression between JDK 11 and JDK 17. Applies cleanly. There is no bugtail in mainline since integration in Nov 2023. All tests pass. Risk is medium, as it touches the common code path for non-Linux platforms, but it is also frequently exercised, and thus a breakage would manifest often.

[openjdk]

@shipilev
8318986: The approval request has been created successfully.

[openjdk]

@shipilev 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:

8318986: Improve GenericWaitBarrier performance

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been no new commits pushed to the master branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[shipilev]

@GoeLin, @jerboaa -- would you mind approving it for 21u? We seem to be in agreement about this plan, see the JBS comments.

[shipilev]

/integrate

[openjdk]

Going to push as commit 6c5500b.
Since your change was applied there has been 1 commit pushed to the master branch:

• f0f2e70: 8326936: RISC-V: Shenandoah GC crashes due to incorrect atomic memory operations

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit 6c5500b.

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