From time to time, Eclipse throws an OutOfMemoryError, complaining that it is out of PERM GEN space. A bit of reading reveals that PERM GEN space is used as a garbage collection generation space for permanent objects -- such as pieces of classes that are never unloaded. You can get this error if you load lots of classes. To increase the size of the PERM GEN space, use:
-XX:MaxPermSize=128m
The default is 64m.