8358621: Reduce busy waiting in worse case at the synchronization point returning from native in CPU Time Profiler

[parttimenerd]

Hi all,

This pull request contains a backport of commit d2082c58 from the openjdk/jdk repository.

The commit being backported was authored by Johannes Bechberger on 15 Jul 2025 and was reviewed by Aleksey Shipilev, Jaroslav Bachorik and Erik Gahlin.

Thanks!

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8358621: Reduce busy waiting in worse case at the synchronization point returning from native in CPU Time Profiler (Bug - P3)

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/26320/head:pull/26320
$ git checkout pull/26320

Update a local copy of the PR:
$ git checkout pull/26320
$ git pull https://git.openjdk.org/jdk.git pull/26320/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 26320

View PR using the GUI difftool:
$ git pr show -t 26320

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/26320.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back jbechberger! A progress list of the required criteria for merging this PR into jdk25 will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@parttimenerd 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:

8358621: Reduce busy waiting in worse case at the synchronization point returning from native in CPU Time Profiler Reviewed-by: shade 

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 15 new commits pushed to the jdk25 branch:

• 07bb0e3: 8362097: JFR: Active Settings view broken
• 60196a6: 8361952: Installation of MethodData::extra_data_lock() misses synchronization on reader side
• 0e6bf00: Merge
• ... and 12 more: https://git.openjdk.org/jdk/compare/7aa3f31724844bf2f4e08111af8173b5d985f809...jdk25

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.

➡️ To integrate this PR with the above commit message to the jdk25 branch, type /integrate in a new comment.

[openjdk]

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

[openjdk]

@parttimenerd The following label will be automatically applied to this pull request:

• hotspot-jfr

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 00: Full (4153486f)

[parttimenerd]

/integrate :jdk25

[openjdk]

@parttimenerd The given argument, :jdk25, is not a valid hash.

[parttimenerd]

/integrate

[openjdk]

Going to push as commit 533211a.
Since your change was applied there have been 15 commits pushed to the jdk25 branch:

• 07bb0e3: 8362097: JFR: Active Settings view broken
• 60196a6: 8361952: Installation of MethodData::extra_data_lock() misses synchronization on reader side
• 0e6bf00: Merge
• ... and 12 more: https://git.openjdk.org/jdk/compare/7aa3f31724844bf2f4e08111af8173b5d985f809...jdk25

Your commit was automatically rebased without conflicts.

[openjdk]

@parttimenerd Pushed as commit 533211a.

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