RFR: 8373096: JFR: Path-to-gc-roots search should be non-recursive [v3]

[Erik Gahlin]

On Thu, 29 Jan 2026 11:00:49 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> test/jdk/jdk/jfr/jcmd/TestJcmdDumpPathToGCRootsDFSBase.java line 67:
>> 
>>> 65:                 File recording = new File(jfrFileName + r.getId() + ".jfr");
>>> 66:                 recording.delete();
>>> 67:                 JcmdHelper.jcmd("JFR.dump", "name=dodo", pathToGcRoots, "filename=" + recording.getAbsolutePath());
>> 
>> Why do we need to do this using jcmd?
>
> Hmm, I just followed the same approach as `TestJcmdDumpPathToGCRoots`. I guess the alternative would be to start a child process JVM with -XX:StartFlightRecording dumponexit=true?

This is how I would implement it:
[patch.txt](https://github.com/user-attachments/files/24935579/patch.txt)

- Put all relevant information in the test file so that, when it fails, it can be easily analyzed without having to flip back and forth between a base class during triage, for example.
- Dump data programmatically, as it is quicker and easier to understand.
- Use the Events class to dump and extract and recording data.
- Place helper methods in the OldObjects class for reuse.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29382#discussion_r2741301803