JFR internal error while printing with OpenJ9-collected data

[0xdaryl]

I'm seeing a jfr internal error printing the result of a JFR collection with OpenJ9 JDK 21:

jfr print foo4.jfr

jfr print: unexpected internal error, Range [1, -1) out of bounds for length 6
java.lang.StringIndexOutOfBoundsException: Range [1, -1) out of bounds for length 6
        at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:55)
        at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:52)
        at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:213)
        at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:210)
        at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:98)
        at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckFromToIndex(Preconditions.java:112)
        at java.base/jdk.internal.util.Preconditions.checkFromToIndex(Preconditions.java:349)
        at java.base/java.lang.String.checkBoundsBeginEnd(String.java:5640)
        at java.base/java.lang.String.substring(String.java:3599)
        at jdk.jfr/jdk.jfr.internal.tool.PrettyWriter.formatMethod(PrettyWriter.java:465)
        at jdk.jfr/jdk.jfr.internal.tool.PrettyWriter.printJavaFrame(PrettyWriter.java:449)
        at jdk.jfr/jdk.jfr.internal.tool.PrettyWriter.printValue(PrettyWriter.java:311)
        at jdk.jfr/jdk.jfr.internal.tool.PrettyWriter.printStackTrace(PrettyWriter.java:247)
        at jdk.jfr/jdk.jfr.internal.tool.PrettyWriter.print(PrettyWriter.java:225)
        at jdk.jfr/jdk.jfr.internal.tool.PrettyWriter.print(PrettyWriter.java:75)
        at jdk.jfr/jdk.jfr.internal.tool.EventPrintWriter.print(EventPrintWriter.java:82)
        at jdk.jfr/jdk.jfr.internal.tool.Print.execute(Print.java:165)
        at jdk.jfr/jdk.jfr.internal.tool.Main.main(Main.java:92)

This fails with a 0.57 JDK 21 build on x86-64, as well as latest Semeru nightly build on JDK 21.

BusyWorkTest.java

openjdk version "21.0.11-beta" 2026-04-21
IBM Semeru Runtime Open Edition 21.0.11+7-202603211948 (build 21.0.11-beta+7-202603211948)
Eclipse OpenJ9 VM 21.0.11+7-202603211948 (build 21.0.11-beta+7-202603211948-master-5354e076b7, JRE 21 Linux amd64-64-Bit Compressed References 20260321_754 (JIT enabled, AOT enabled)
OpenJ9   - 5354e076b7
OMR      - db4e13717
JCL      - 02a7b880f based on jdk-21.0.11+7)

OpenJDK does not have this problem, nor does OpenJ9 jfr have a problem with printing OpenJDK-collected data. However, OpenJDK fails with the same error on OpenJ9-collected data. Both facts lead me to suspect the problem is on the OpenJ9 collection side.

I've seen this on a couple of different applications, but I've attached an IBM Bob-generated test (BusyWorkTest.java) just for this purpose that shows the problem. To reproduce:

java -XX:+FlightRecorder BusyWorkTest

and at the 30 second mark, issue the following:

jcmd <vmid> JFR.start filename=foo.jfr duration=60s

and then attempt to print it with:

jfr --print foo.jfr

[0xdaryl]

@tajila : FYI

[tajila]

Hi @0xdaryl

As stated in https://eclipse.dev/openj9/docs/xxflightrecorder/ J9 offers limited JFR support at the moment. We currently do not support the usage of the jfr utility. The only supported way to view jfr files generated by j9 is with JMC.

OpenJDK does not have this problem, nor does OpenJ9 jfr have a problem with printing OpenJDK-collected data.

The jfr utility bundled in j9 is identical to the one in openjdk (we inherit it from the extensions repo). When you use the default print option it relies on a hotspot optimization that keeps constantPool indexes static between jfr chunks which j9 doesnt support currently.

That being said, if you re-run your example with --xml or --json it should work as those suboptions disable the optimization.

:~/jfr$ ./jdk/bin/jfr print --xml  busywork.jfr
<?xml version="1.0" encoding="UTF-8"?>
<recording xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <events>
    <event type="jdk.ExecutionSample">
      <value name="startTime">2026-03-24T03:43:44.160287391-08:00</value>
      <struct name="sampledThread">
        <value name="osName">JFR-Scheduler</value>
        <value name="osThreadId">29443</value>
        <value name="javaName">JFR-Scheduler</value>
        <value name="javaThreadId">4</value>
        <struct name="group">
          <struct name="parent">
            <struct name="parent">
              <struct name="parent" xsi:nil="true"/>
              <value name="name" xsi:nil="true"/>
            </struct>
            <value name="name">system</value>
          </struct>
          <value name="name">main</value>
        </struct>
      </struct>
      <struct name="stackTrace">

[0xdaryl]

Thanks for the clarification. I assumed the jfr tool worked with Semeru because of the examples in this blog post -> https://community.ibm.com/community/user/blogs/harshitha-popuri/2025/05/09/jdk-flight-recorder-jfr-user-guide

Yes, I should have mentioned that I did find that the --json and --xml options worked with Semeru.

[tajila]

Thanks for the clarification. I assumed the jfr tool worked with Semeru because of the examples in this blog post -> https://community.ibm.com/community/user/blogs/harshitha-popuri/2025/05/09/jdk-flight-recorder-jfr-user-guide

That's misleading, I'll try to get it corrected.