Goodbye restarts, Hello Javaleon

Java class reloader Javeleon hits 2.0 release

Chris Mayer

The dynamic update system enters its second series, promising a ‘highly improved’ reloading experience

The world of super-fast class reloaders has certainly become a competitive one in recent years. With JRebel and DCEVM both innovating, what can the Javeleon class reloading system offer this time round in 2.0 that breaks the mould? Seemingly quite a lot. The University of Southern Denmark is behind the tool that lets you see code changes in your running application immediately, and has spent a lot of work boosting performance of Javeleon to further enhance productivity in your working environment. Startup time is much quicker, whilst runtime performance overhead is substantially lowered. Several issues are fixed too, such as a cloning objects bug, resolved JDK 7 problems and a native method issue. The team behind Javeleon also say that 2.0 provides better support for Java dynamic proxies and AspectJ. The ties to the NetBeans IDE are fairly obvious, with Javeleon fitting best into that IDE with strong integration. Javeleon not only comes with out-of-the-box integration for NetBeans Platform-based applications, but also supports GUI development on the IDE. Recent benchmark tests (shown below) show that Javeleon is certainly catching up with JRebel in terms of performance, but there’s really not too much between the two. If you’re still uncertain of which to pick, the comparative features list might help you decide – JRebel has the edge on instant builds and reloading resources, whilst Javeleon can replace superclasses. There’s certainly worth in both. If you’re somehow not using a class reloader in your environment, where have you been? Ready to skip those infuriating restarts? Download Javeleon 2.0 here, for either standalone Javeleon or the NetBeans plugin. Javeleon is a JVM-plug-in that requires to be configured as a JVM agent. This is done by using the “-javaagent” argument in your JVM launch settings. The team are currently looking for JBoss 7.1 beta testers ahead of moving across to that area, contact [email protected] if you want to help out there!


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