[akeefer]

Depending on why you're restarting your VM, you may want to check out the DCEVM: http://java.net/projects/dcevm

It lets you do arbitrary hotswapping of code, rather than only swapping method bodies. Not appropriate for production at this point, but you can install it on top of any Java 6 version prior to update 26 (not sure about Java 7); it's pretty useful for doing rapid iterations during development of large-scale server apps or swing applications.

[ww520]

Does anyone have the documentation or tutorial for DCEVM? I've looked at it from time to time but never able to figure out how to use it. There's no doc beside the jar file.

[akeefer]

Sorry for the late reply (didn't see the question until now). The DCEVM is just a patched version of the JVM dll/so file that allows the normal hotswap mechanism (triggered by JVMTI) to accept arbitrary class changes, rather than just method body changes. There's no additional mechanism or API, it just makes the already-existing mechanism for hotswapping better. To install it, you just run the installer jar and point it to your jdk. To use it, you just trigger a hotswap as you normally would, which generally means starting your program in debug mode via an IDE, and having the IDE automatically swap changes for you as classes change locally. If you want to do hotswapping without the IDE, that's a bit trickier. Technically, you can write your own JNI code to directly hook into JVMTI and trigger a hotswap (which is what we actually do with our development platform at Guidewire), but the easiest way to do it is generally just to use the debug capabilities of the IDE.