RFR: 8365400: enhance JFR to emit file and module metadata for class loading

Mon Oct 6 22:42:45 UTC 2025

On Mon, 6 Oct 2025 18:15:51 GMT, Larry Cable <duke at openjdk.org> wrote:

> while existing class loading JFR events exist, none of these provide the path (if available) from which a class is loaded/defined, nor are they easily modified to do so from a compatibility standpoint.
> 
> therefore this ER/PR adds a simple JFR event that encapsulates a tuple of class and path that can be enabled in order to provide an audit/debug trail of locations (path, if available) from which a particular class is loaded/defined.
> 
> this association can be used for various "applications" such as basic auditing etc

sounds good, will do so!

thx

On 10/6/25 3:33 PM, Erik Gahlin wrote:
> *egahlin* left a comment (openjdk/jdk#27656) 
> <https://urldefense.com/v3/__https://github.com/openjdk/jdk/pull/27656*issuecomment-3374488908__;Iw!!ACWV5N9M2RV99hQ!LsYP65VL4wbG0567H5u0fobZGwD-AhgqyFUXDwC7LTnVDAop8HdvYCAzZLBn4QogqPSZA-LReG2opO6WMvYfxMeLZw$>
>
> I have not reviewed SecureClassLoader, as this is better done by 
> people who are more knowledgeable in the area. That said, 
> toExternalForm() appears to be a somewhat expensive function, so you 
> may want to add a guard. Also check for null.
>
> |ClassFileDefineEvent evt = new ClassFileDefineEvent(); if 
> (event.shouldCommit()) { event.definedClass = cls; if (cs != null) { 
> URL location = cs.getLocation(); if (location != null) { event = 
> location.toExternalForm(); } } event.commit(); } |
>
> Could you also add the event to profile.jfc? Please remove "Name" from 
> the label "Defined Class Name," as the whole class is serialized, and 
> add a test to test/jdk/jdk/jfr/event/runtime.
>
> —
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    sounds good, will do so!<br>
    <br>
    thx<br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 10/6/25 3:33 PM, Erik Gahlin wrote:<br>
    </div>
    <blockquote type="cite" ***@***.***">

      <div style="display: flex; flex-wrap: wrap; white-space: pre-wrap; align-items: center; "><img height="20" width="20" style="border-radius:50%; margin-right: 4px;" decoding="async" src="https://avatars.githubusercontent.com/u/43493071?s=20&v=4" moz-do-not-send="true"><strong>egahlin</strong> left a comment <a href="https://urldefense.com/v3/__https://github.com/openjdk/jdk/pull/27656*issuecomment-3374488908__;Iw!!ACWV5N9M2RV99hQ!LsYP65VL4wbG0567H5u0fobZGwD-AhgqyFUXDwC7LTnVDAop8HdvYCAzZLBn4QogqPSZA-LReG2opO6WMvYfxMeLZw$" moz-do-not-send="true">(openjdk/jdk#27656)</a></div>
      <p dir="auto">I have not reviewed SecureClassLoader, as this is
        better done by people who are more knowledgeable in the area.
        That said, toExternalForm() appears to be a somewhat expensive
        function, so you may want to add a guard. Also check for null.</p>
      <pre class="notranslate"><code class="notranslate">    ClassFileDefineEvent evt = new ClassFileDefineEvent();
    if (event.shouldCommit()) {
        event.definedClass = cls;
        if (cs != null) {
            URL location = cs.getLocation();
            if (location != null) {
                event = location.toExternalForm();
            }
        }
        event.commit();   
    }
</code></pre>
      <p dir="auto">Could you also add the event to profile.jfc? Please
        remove "Name" from the label "Defined Class Name," as the whole
        class is serialized, and add a test to
        test/jdk/jdk/jfr/event/runtime.</p>
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PR Comment: https://git.openjdk.org/jdk/pull/27656#issuecomment-3374507982