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8211230 JFR: internal events #6764

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@egahlin egahlin commented Dec 8, 2021


Could I have review of a fix that adds internal events.

Internal events are for Hotspot developers so they can easily create events for temporary measurements without the need to modify .jfc file etc.

The code that commits internal events are never meant to go Into the product and could be seen as a low overhead alternative to printf statements. Internal events are "registered" with JFR when the commit() method is called. If it is never invoked, the event will remain hidden.

The ZThreadDebug is turned into an internal event, so it is not visible in product and four new internal events are added "EventDuration", "EventInstant", "EventValue" and "EventText". Example usage:

    #include "jfr/jfrEvents.hpp"

    void foo() {
      EventDuration event;

To build and show events:

    $ make images
    $ java -XX:StartFlightRecording:settings=none,filename=dump.jfr ...  
    $ jfr print dump.jfr

Programmatic access:

    try (var rf = new RecordingFile(Path.of("dump.jfr)) {
        while (rf.hasMoreEvent()) {
            RecordedEvent e = rf.readEvent();
            System.out.println(e.getName() + " " + e.getDuration()));

Testing: jdk/jdk/jfr



  • Change must not contain extraneous whitespace
  • Commit message must refer to an issue
  • Change must be properly reviewed




Using git

Checkout this PR locally:
$ git fetch pull/6764/head:pull/6764
$ git checkout pull/6764

Update a local copy of the PR:
$ git checkout pull/6764
$ git pull pull/6764/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 6764

View PR using the GUI difftool:
$ git pr show -t 6764

Using diff file

Download this PR as a diff file:

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@bridgekeeper bridgekeeper bot commented Dec 8, 2021

👋 Welcome back egahlin! 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.

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@openjdk openjdk bot commented Dec 8, 2021

@egahlin The following labels will be automatically applied to this pull request:

  • build
  • hotspot-jfr

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

@openjdk openjdk bot added build hotspot-jfr labels Dec 8, 2021
@egahlin egahlin marked this pull request as ready for review Dec 8, 2021
@openjdk openjdk bot added the rfr label Dec 8, 2021
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@mlbridge mlbridge bot commented Dec 8, 2021

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@mgronlun mgronlun left a comment

Looks good. Nice feature.

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@openjdk openjdk bot commented Dec 9, 2021

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

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

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

8211230: JFR: internal events

Reviewed-by: mgronlun

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 openjdk bot added the ready label Dec 9, 2021
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@egahlin egahlin commented Dec 9, 2021


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@openjdk openjdk bot commented Dec 9, 2021

Going to push as commit 08aad85.

@openjdk openjdk bot closed this Dec 9, 2021
@openjdk openjdk bot added integrated and removed ready rfr labels Dec 9, 2021
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@openjdk openjdk bot commented Dec 9, 2021

@egahlin Pushed as commit 08aad85.

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

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