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The "OutOfMemoryError: PermGen space" exception is normally encountered in development process where a long-running JVM is asked to reload builds.

Use the JVM options -XX:+TraceClassloading and -XX:+TraceClassUnloading to see what classes are loaded/un-loaded in real-time. If you have doubts about excessive class loading in your app; this might help you find out exactly what classes are loaded and where. Use -XX:+UseParallelGC to tell the JVM to use multi-threaded, one thread per CPU, garbage collection. This might improve GC performance since the default garbage collector is single-threaded. Define the number of GC threads to use with the -XX:ParallelGCThreads={no of threads} option Never call System.gc(). The application doesn't know the best time to garbage-collect, only the JVM really does. The JVM option -XX:+AggressiveHeap inspects the machine resources (size of memory and number of processors) and attempts to set various heap and memory parameters to be optimal for long-running, memory allocation-intensive jobs.

This is not optimization tip, but... do you know...? that Java (JVM) limits the amount of code to 64kB per Java method. Sometimes, as the JSPs grow larger, there is a possibility of hitting this limit.