Cannot run JFR profiler on JDK9/macos

I noticed that I couldn’t self-profile the gradle-profiler build (task help) when running JDK9. JDK8 works fine. I don’t know yet whether this is a JDK/platform issue, or something to do with how gradle-profiler interacts with the profiler/instrumentation.

JDK/platform:

$ java -version
java version "9.0.4"
Java(TM) SE Runtime Environment (build 9.0.4+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.4+11, mixed mode)

$ uname -a
Darwin <redacted> 17.4.0 Darwin Kernel Version 17.4.0: Sun Dec 17 09:19:54 PST 2017; root:xnu-4570.41.2~1/RELEASE_X86_64 x86_64

Build gradle-profiler then run:

./gradlew installDist
./build/install/gradle-profiler/bin/gradle-profiler --project-dir . --profile jfr --warmups 10 --iterations 10 help

Output:

* Stopping profiler for daemon with pid 73537
Could not load the JFR file.
If the JFR file is compressed, try the decompress option
java.io.FileNotFoundException: /<redacted>/gradle-profiler/profile-out/4.8.jfr (No such file or directory)

Cause in profile-out/profile.log:

* Using args for instrumented builds:

* Starting profiler for daemon with pid 73537
73537:
Could not parse setting /var/folders/k3/pl9l2b3x1sbgzqf_m2n5gfpw0000gn/T/gradle8260768521305363072.jfc

* Running measured build #1 with build tasks [help]

I’ve not yet been able to capture a jfc file or determine any cause. Please advise if any debugging or verbose logging can be added to a run.

[javabrett]

I checked and the .jfc file format seems to have been version-revved for JDK9, there are at least minor schema changes and they are neither forward nor backward compatible. I predict that a different or filtered version of the modified profile config gradle.jfc is going to be needed for JDK8 and 9.

JDK8: <configuration version="1.0" name="Profiling" description="Low overhead configuration for profiling, typically around 2 % overhead." provider="Oracle">

JDK9: <configuration version="2.0" label="Profiling" description="Low overhead configuration for profiling, typically around 2 % overhead." provider="Oracle">

Note version and addition of label at least. I don’t know yet what other schema changes might be in-effect. Testing log below, on macos but same on Linux with Oracle JDK.

$ ./gradlew -Dorg.gradle.jvmargs="-XX:+UnlockCommercialFeatures -XX:+FlightRecorder" help

$ jcmd
1795 org.gradle.launcher.daemon.bootstrap.GradleDaemon 4.8

$ jcmd 1795 JFR.start settings=src/main/resources/org/gradle/profiler/jfr/gradle.jfc
1795:
Could not parse setting src/main/resources/org/gradle/profiler/jfr/gradle.jfc

$ jcmd 1795 JFR.start settings=/Library/Java/JavaVirtualMachines/jdk-9.0.4.jdk/Contents/Home/lib/jfr/profile.jfc
1795:
Started recording 1. No limit specified, using maxsize=250MB as default.

Use JFR.dump name=1 filename=FILEPATH to copy recording data to file.

[oehme]

I made it run on Java 9, though it won’t produce flame graphs yet (see https://github.com/gradle/gradle-profiler/issues/77). That API has changed too 😕