8352251: Implement JEP 518: JFR Cooperative Sampling #24296

mgronlun · 2025-03-28T15:38:59Z

Greetings,

This is the implementation of JEP JDK-8350338 Cooperative JFR Sampling.

Implementations in this change set are provided and have been tested on the following platforms:

windows-x64
windows-x64-debug
linux-x64
linux-x64-debug
macosx-x64
macosx-x64-debug
linux-aarch64
linux-aarch64-debug
macosx-aarch64
macosx-aarch64-debug

Testing: tier1-6, jdk_jfr, stress testing.

Platform porters note:
Some platform-specific code needs to be provided, mainly in the interpreter. Take a look at the following files for changes:

src/hotspot/cpu/x86/frame_x86.cpp
src/hotspot/cpu/x86/interp_masm_x86.cpp
src/hotspot/cpu/x86/interp_masm_x86.hpp
src/hotspot/cpu/x86/javaFrameAnchor_x86.hpp
src/hotspot/cpu/x86/macroAssembler_x86.cpp
src/hotspot/cpu/x86/macroAssembler_x86.hpp
src/hotspot/cpu/x86/templateInterpreterGenerator_x86.cpp
src/hotspot/cpu/x86/templateTable_x86.cpp
src/hotspot/os_cpu/linux_x86/javaThread_linux_x86.hpp

Thanks
Markus

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
Change requires a JEP request to be targeted

Issues

JDK-8352251: Implement JEP 518: JFR Cooperative Sampling (Sub-task - P2)
JDK-8350338: JEP 518: JFR Cooperative Sampling (JEP)

Reviewers

Erik Österlund (@fisk - Reviewer)
Erik Gahlin (@egahlin - Reviewer)

Contributors

Aleksey Shipilev <shade@openjdk.org>
Erik Österlund <eosterlund@openjdk.org>
Boris Ulasevich <bulasevich@openjdk.org>
Patricio Chilano Mateo <pchilanomate@openjdk.org>
Martin Doerr <mdoerr@openjdk.org>
Fei Yang <fyang@openjdk.org>
Amit Kumar <amitkumar@openjdk.org>

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/24296/head:pull/24296
$ git checkout pull/24296

Update a local copy of the PR:
$ git checkout pull/24296
$ git pull https://git.openjdk.org/jdk.git pull/24296/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 24296

View PR using the GUI difftool:
$ git pr show -t 24296

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/24296.diff

Using Webrev

Link to Webrev Comment

bridgekeeper · 2025-03-28T15:39:54Z

👋 Welcome back mgronlun! 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 · 2025-03-28T15:40:01Z

@mgronlun 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:

8352251: Implement JEP 518: JFR Cooperative Sampling

Co-authored-by: Aleksey Shipilev <shade@openjdk.org>
Co-authored-by: Erik Österlund <eosterlund@openjdk.org>
Co-authored-by: Boris Ulasevich <bulasevich@openjdk.org>
Co-authored-by: Patricio Chilano Mateo <pchilanomate@openjdk.org>
Co-authored-by: Martin Doerr <mdoerr@openjdk.org>
Co-authored-by: Fei Yang <fyang@openjdk.org>
Co-authored-by: Amit Kumar <amitkumar@openjdk.org>
Reviewed-by: eosterlund, egahlin

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.

openjdk · 2025-03-28T15:40:46Z

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

hotspot

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 · 2025-03-28T15:44:24Z

Webrevs

mgronlun · 2025-03-28T15:54:03Z

/label add hotspot-jfr

openjdk · 2025-03-28T15:54:58Z

@mgronlun
The hotspot-jfr label was successfully added.

shipilev

A drive-by comment, since I am cleaning up some of x86 code after x86_32 removals:

src/hotspot/cpu/x86/interp_masm_x86.cpp

mgronlun · 2025-04-07T08:58:48Z

Friendly reminder/heads-up to platform and port maintainers:

Please review the necessary platform changes in advance so that your port will be ready once this integration is complete. Alternatively, you can send me your change sets for them to be incorporated into this PR.

Thanks
Markus

src/hotspot/share/jfr/periodic/sampling/jfrThreadSampling.cpp

src/hotspot/share/jfr/recorder/service/jfrEventThrottler.cpp

src/hotspot/share/jfr/recorder/stacktrace/jfrStackTrace.cpp

src/hotspot/share/jfr/recorder/stacktrace/jfrVframeStream.hpp

openjdk · 2025-04-18T22:21:11Z

⚠️ @mgronlun This pull request contains merges that bring in commits not present in the target repository. Since this is not a "merge style" pull request, these changes will be squashed when this pull request in integrated. If this is your intention, then please ignore this message. If you want to preserve the commit structure, you must change the title of this pull request to Merge <project>:<branch> where <project> is the name of another project in the OpenJDK organization (for example Merge jdk:master).

shipilev · 2025-04-23T08:44:17Z

Zero does not use JFR, jfr build feature flag is not enabled. So we only need to make sure it compiles. It currently does not, because last_Java_fp returns ZeroFrame*, and not generic intptr_t*. Here: jfr-cooperative-zero-1.txt

mgronlun · 2025-04-23T19:27:15Z

Zero does not use JFR, jfr build feature flag is not enabled. So we only need to make sure it compiles. It currently does not, because last_Java_fp returns ZeroFrame*, and not generic intptr_t*. Here: jfr-cooperative-zero-1.txt

Thanks alot @shipilev . It was precisely this "ZeroFrame*" that tripped me up.

mgronlun · 2025-04-23T19:42:36Z

/contributor add @shipilev

openjdk · 2025-04-23T19:43:05Z

@mgronlun
Contributor Aleksey Shipilev <shade@openjdk.org> successfully added.

TheRealMDoerr · 2025-05-26T14:49:28Z

Rebased version is here: TheRealMDoerr@e98c21e
I think I have all parts which have been implemented for other platforms. I can continue testing the whole PR after it is integrated.

mgronlun · 2025-05-26T15:02:15Z

Rebased version is here: TheRealMDoerr@e98c21e I think I have all parts which have been implemented for other platforms. I can continue testing the whole PR after it is integrated.

Great. Integrated.

fisk

I see you fixed the JVMTI issue. This looks good to me now.

mgronlun · 2025-05-26T15:47:36Z

I see you fixed the JVMTI issue. This looks good to me now.

Thank you very much, Erik!

offamitkumar · 2025-05-26T15:50:25Z

Hi @mgronlun ,

Please include the minimal build fix for s390x from here: offamitkumar@916efec . I need to port some other enhancement before I can complete this one. So I am planning it for later.

mgronlun · 2025-05-26T16:23:26Z

Hi @mgronlun ,

Please include the minimal build fix for s390x from here: offamitkumar@916efec . I need to port some other enhancement before I can complete this one. So I am planning it for later.

Thanks Amit. Integrated.

mgronlun · 2025-05-26T16:23:55Z

/contributor add @offamitkumar

openjdk · 2025-05-26T16:24:48Z

@mgronlun
Contributor Amit Kumar <amitkumar@openjdk.org> successfully added.

mgronlun · 2025-05-26T16:56:09Z

Thank you, @fisk and @egahlin, for your reviews!

mgronlun · 2025-05-26T18:37:02Z

/integrate

openjdk · 2025-05-26T18:38:00Z

Going to push as commit bbceab0.
Since your change was applied there has been 1 commit pushed to the master branch:

e8eff4d: 8357530: C2 SuperWord: Diagnostic flag AutoVectorizationOverrideProfitability

Your commit was automatically rebased without conflicts.

openjdk · 2025-05-26T18:38:08Z

@mgronlun Pushed as commit bbceab0.

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

mgronlun · 2025-05-26T18:43:16Z

Thank you all for contributing, reviewing, providing recommendations, and supporting getting this feature ready for JDK 25.

Many thanks
Markus

8352251

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openjdk bot added the rfr Pull request is ready for review label Mar 28, 2025

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mgronlun added 3 commits March 28, 2025 22:19

refactoring

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Merge branch 'master' into 8352251

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Merge branch 'master' into 8352251

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mgronlun added 6 commits April 19, 2025 00:26

Merge branch '8352251' of github.com:mgronlun/jdk into 8352251

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review comments

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Update profile.jfc

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Refine SamplingLatency event description

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Merge branch 'master' into 8352251

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graalvmbot mentioned this pull request Jun 2, 2025

[GR-65447] Update labsjdk to 25+25-jvmci-b01 oracle/graal#11300

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8352251: Implement JEP 518: JFR Cooperative Sampling #24296

8352251: Implement JEP 518: JFR Cooperative Sampling #24296

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