Is there a way to check if a particular jdk (Oracle or OpenJDK) supports Java Flight Recorder?

Question

Is there a way to check if a particular jdk (Oracle or OpenJDK) supports Java Flight Recorder? I have been trying to run my app on OPEN JDK 8 as following

java -XX:StartFlightRecording

But this does not work on OPEN JDK 8 . I get following error Unrecognized VM option -XX:+UnlockCommercialFeatures

but does not work

Answer 1

You need to 'unlock the commercial features' as described here:
https://docs.oracle.com/javacomponents/jmc-5-4/jfr-runtime-guide/run.htm#JFRUH176

The command should look like this:

java -XX:+UnlockCommercialFeatures -XX:+FlightRecorder -XX:StartFlightRecording=duration=60s,filename=myrecording.jfr MyApp

Answer 2

One way to check if a JVM supports JFR is to do:

$ jdb

Open a second shell.

$ jcmd

Remember the pid of the jdb process and do:

$ jcmd <pid> help

If the JVM list diagnostic commands starting with JFR, it is supported. If the JDK lacks jcmd, JFR is not supported (unless it is a JRockit JVM in which case jcmd is called jrcmd and the command to look for is start_flightrecording).