Collecting Java Flight Recording (JFR) on openjdk

From OpenJDK 8u262 has JFR support as its backported with - JDK-8223147: JFR Backport.

Following is just in case if you want to use JFR on openjdk (possible through azul). We just azul opnjdk and it works on my lab instance for collecting JFR. In case in future if anyone wants to use all steps.

With openjdk JFR compress=true don’t work but settings=profile does work.

Java Mission Control from oracle was not able to read the file but you can use zulu zmc .

To download azul OSS jdk

https://www.azul.com/downloads/zulu-community/?architecture=x86-64-bit&package=jdk

As my default JMC did not work with .jfr generated by zing jdk I used following.

https://www.azul.com/products/zulu-mission-control/

• Unlock commercial features.

sudo -u <user> jcmd <pid>  VM.unlock_commercial_features

• Start JFR collection with settings=profile

sudo -u <user> jcmd <PID> JFR.start name=<jfr_name> settings=profile

• Dump JFR

sudo -u <user> jcmd <PID> JFR.dump name=<jfr_name> filename=/tmp/`hostname -i`.jfr

• Make sure JFR file is generated.

ls -lrt /tmp/`hostname -i`.jfr

• Stop JFR process

sudo -u <user> /usr/lib/jvm/java-1.8.0-openjdk/bin/jcmd  <PID> JFR.stop name=<jfr_name>

• Check if any additional JFR process are runing and stop if its not in use

sudo -u <user> jcmd <PID> JFR.check