the sneaky OutOfMemoryError: PermGen space error

Today I ran into several VERY nice posts which talk about the PermGen errors.

Here are Frank Kieviet's two blogs: classloader leakers and how to fix it (more like how to find it, fixing is likely to be the easy part).

Here is an excellent list of known offenders and links from Spring forum. link.

I cannot wait to modify jhat to map out the heap of my applications. We actually have two applications that are suffering from PermGen errors. One interesting point is that both applications suffer this error when they are hot deployed (unload then load while the application server is running) and when they run for a prolonged period of time. It seems like the first scenario is well examined. It will be very interesting to see what I can find out on the second scenario.