[Native Image] JFR: Exception occurred during execution of flush task

[dekelpilli]

Describe the Issue

I was trying to use JFR to help debug an issue I was having, but the recording would remain empty, with the following log line appearing over and over again while the app was running:

[warn][jfr,system ] Exception occurred during execution of flush task

I've set up this repo to reproduce this issue - https://github.com/dekelpilli/graalvm-jfr-bug. It's worth noting that in its current state, the error does not always appear, but re-compiling will often make it appear again.

Using the latest version of GraalVM can resolve many issues.

• I tried with the latest version of GraalVM.

GraalVM Version

java version "23.0.1" 2024-10-15
Java(TM) SE Runtime Environment Oracle GraalVM 23.0.1+11.1 (build 23.0.1+11-jvmci-b01)
Java HotSpot(TM) 64-Bit Server VM Oracle GraalVM 23.0.1+11.1 (build 23.0.1+11-jvmci-b01, mixed mode, sharing)

Also, as this is using clojure:

$ clojure --version
Clojure CLI version 1.12.0.1517

Operating System and Version

Darwin Mac 24.3.0 Darwin Kernel Version 24.3.0: Thu Jan 2 20:24:23 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T6031 arm64

Troubleshooting Confirmation

• I tried the suggestions in the troubleshooting guide.

Run Command

./target/graal-memory-test -XX:StartFlightRecording=filename=recording.jfr

Expected Behavior

recording.jfr is populated with JFR data during the application's runtime.

Actual Behavior

The file is created but remains empty, and the application logs the following a few times per second:

[warn][jfr,system ] Exception occurred during execution of flush task

Steps to Reproduce

From the graalvm-jfr-bug repo, ./compile.sh && ./run.sh. This requires Clojure to be installed.

If this correctly creates JFR data, simply run this again until it doesn't. In my experience, it ends up working about 50% of the time.

I wasn't able to attach them to this issue, but I've committed bundles of both a working and a non-working compilation:
https://github.com/dekelpilli/graalvm-jfr-bug/blob/master/error_not_present_bundle.nib
https://github.com/dekelpilli/graalvm-jfr-bug/blob/master/error_present_bundle.nib

Additional Context

No response

Run-Time Log Output and Error Messages

[warn][jfr,system ] Exception occurred during execution of flush task

[roberttoyonaga]

Hi @dekelpilli. Thanks for reporting this. I was able to reproduce the problem using the example you provided. I have made a fix here: #10749

If you'd like to try out the fix on my branch yourself, here are some instructions on building GraalVM from source:
You need the mx build tool. You also need the latest labsjdk release.

Put mx on the path and set java home to labsjdk:
export PATH=/path/to/mx:$PATH
export JAVA_HOME=/path/to/labsjdk
Run mx --dynamicimports /substratevm build from the vm directory. And then run mx build from the graal/substratevm directory.
Then you can use mx native-image, or just find the native-image binary in the build directory graal/vm/latest_graalvm_home/bin/native-image.

The first few minutes of this video does a good job of explaining this as well: https://youtu.be/3Gh0cz3vjG8?feature=shared&t=202