PermGen Space is a part of jvm memory where classes are loaded.
There are couple of reasons why you can get PermGen Space errors. Most common are:
- There are really lots of classes to be loaded by your app (this is rather rare case for typical application that runs on Oracle JVM). You can solve this by increasing your PermGen Space (see how to configure your jvm).
- There are classloader leaks in your app. In this case you should find and eliminate them. Read this and this article series for some tips on how to solve this.