Oracle JDK 11 emits a warning when using the -XX:+UnlockCommercialFeatures option, whereas OpenJDK doesn’t recognize this option and reports an error. If you are used to getting Oracle JDK binaries for free, download OpenJDK builds instead, they’re functionally identical.Īs a consequence, JFR is now open source and simplifying the release process with a single code base renders the OpenJDK more appealing to developers. Eventually, starting with Java 11, Oracle provides JDK releases under the open-source GPL and a commercial license. To make a long story short, in order to achieve shorter release times, they’re now working on a single code base that made Oracle JDK and OpenJDK builds interchangeable. Nevertheless, Java SE, since version 9, has got a predictable six-month release cycle. I think he might have thought of Ubuntu, although he didn’t mention that specifically. Mark Reinhold at Oracle wanted to move Java forward faster and took inspiration from some Linux operating systems that have a release cadence of six months. In practice, you could enable it with the -XX:+UnlockCommercialFeatures -XX:+FlightRecorder flags, and earlier JVMs wouldn’t enforce having a license key or anything else like that.
Java Flight Recorder Went Open SourceĪs I mentioned in the intro, this one used to be a proprietary feature of the Oracle JDK, and officially, it was only available for paying, Oracle customers. JFR collects data about the running threads, GC cycles, locks, sockets, memory usage, and a lot more. Of course, not all of the issues are that severe. An anomaly can be seen from its first emergence as it unfolds and, finally, until that point when it causes the application to die. For short running apps, this overhead might be above that because JFR requires some warm-up time on the start.ĭiagnosing faulty apps with JFR might shorten resolution times significantly. Its performance overhead is negligible and that’s usually below 1 percent.
JFR is a profiling tool used to gather diagnostics and profiling data from a running Java application. Therefore, I thought it was worth writing a fresh post on using JFR with OpenJDK 11. JFR, previous proprietary solution, might be lesser known for those relying on previous versions of OpenJDK. As it’s been open sourced along with Java Mission Control, everyone using OpenJDK 11 can now troubleshoot their Java apps with this excellent tool for free of charge. Java Flight Recorder (JFR) used to be a commercial add-on of the Oracle JDK.
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