Finding Java Thread Leaks with JDK Flight Recorder and a Bit of SQL

JFR is one of my favourite Java features. Like eBPF but with more events baked into the runtime and easier to use.<p>Gunnar has used it in some cool ways. Not just <a href="https:&#x2F;&#x2F;github.com&#x2F;moditect&#x2F;jfr-analytics">https:&#x2F;&#x2F;github.com&#x2F;moditect&#x2F;jfr-analytics</a>, which he showcases in this post, but also <a href="https:&#x2F;&#x2F;github.com&#x2F;moditect&#x2F;jfrunit">https:&#x2F;&#x2F;github.com&#x2F;moditect&#x2F;jfrunit</a>

Say what you will about Java, but its tooling is not lacking.

&gt; and the stack trace of the parent thread when starting the child thread<p>That&#x27;s incredibly useful. We have a strict policy of all threads and pools being named, but sometimes default named threads sneak in making it difficult to figure out where the thread is used for.

Java is not the most appealing programming language, but you&#x27;ve got to love the JVM, the standard library, all the libraries and frameworks, plus the tooling around the ecosystem.

I need to learn to use jfr apparently. Just something I’ve known existed and never used.<p>We attach a hawtio.io jvm agent to every single prod jvm we run and query the agent using telegraph. (If you don’t do this by the way, you should!) I noticed in the GUI portion of hawtio, it slows you to start&#x2F;stop a jfr recording, but I’ve never messed with it

HN being very anti Java, why does such many Java articles make it to the front page?

JFR is nice but I can&#x27;t seem to find issues as easily with the new JMC as I used to 5.5 or before. I&#x27;m not sure what I&#x27;m doing wrong though.

For a split second there, I thought a post-airline accident flight recorder had some Java heap dumps that showed major issues and thread leaks.