8211230 JFR: internal events

[egahlin]

Hi,

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;
      bar();
      baz();
      event.commit();
    }

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

Thanks
Erik

---

Progress

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Issue

• JDK-8211230: JFR: internal events

Reviewers

• Markus Grönlund (@mgronlun - Reviewer)

Reviewing

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[mlbridge]

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[mgronlun]

Looks good. Nice feature.

[openjdk]

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

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8211230: JFR: internal events

Reviewed-by: mgronlun

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[egahlin]

/integrate

[openjdk]

Going to push as commit 08aad85.

[openjdk]

@egahlin Pushed as commit 08aad85.

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