Disclaimer: A Word On Licensing
The tooling is part of the Oracle JDK downloads. In particular the JMC 5.4 is part of JDK 8u20 and JDK 7u71 and is distributed under the Oracle Binary Code License Agreement for Java SE Platform products and commercially available features for Java SE Advanced and Java SE Suite. IANAL, but as far as I know this allows for using it for your personal education and potentially also as part of your developer tests. Make sure to check back with whomever you know that could answer this question. This blog post looks at it as a small little how-to and assumes, that you know what you are doing from a license perspective.
Adding Java Optional Parameters
Unlocking the JFR features requires you to put in some optional parameters to your WildFly 8.x/EAP 6.x configuration. Find the $JBOSS_HOME/bin/standalone.conf|conf.bat and add the following parameters:
You can now use jcmd command like described in this knowledge-base entry to start a recording. Another way is actually to start a recording directly from JMC.
Starting A Recording From JMC
at the documentation for all the details. What is really interesting is the function to start a Flight Recording. If you select this option, a new wizard pops up and lets you tweak the settings a bit. Beside having to select a folder where the recording gets stored you also have the choice between different recording templates.
A one minute recording with the "Server Profiling" template with barely any load on the server results in a 1.5 MB file. So, better keep an eye on the volume you're storing all that stuff at.
You can also decide the profiling granularity for a bunch of parameters further down the dialogues. But at the end, you click "Finish" and the recording session starts. You can decide to push it to the background and keep working while the data gets captured.
Analyzing Flight Recorder Files
This is pretty easy. You can open the recording with JMC and click through the results. If you enabled the default recording with the additional parameter:
you can also directly dump the recording via the JVM browser. It is easy to pick a time-frame that you want to download the data for or alternatively you can also decide to download the complete recording.