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Sep 10

How do you find out what’s classes are being stored in PermGen? Trace class loading/unloading

PermGen holds the metadata about classes that have been loaded/created. This information is garbage collected like the other parts of the heap, however there are rough edges that can prevent this from happening, class loaders in particular. Generally, the amount of PermGen space needed is small in relation to the rest of the heap.

How do I know what classes are being loaded or unloaded? Use the command line options

-XX:+TraceClassLoading and -XX:+TraceClassUnloading .

If you suspect that that classloader isn’t the issue, use -verbose:class to investigate classes which have been loaded. This, as it suggests, will be very verbose.

How do you increase PermGen space?

Increase using the -XX:MaxPermSize option.

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