mercoledì 16 febbraio 2011

Increasing Permgen size in your Web Server

In previous posts , we had talked about Increasing the Heap size of your server
Here will talk about the Permgen space , how it is different from heap size and why just increasing the heap size will not help you in getting rid of this error 
Java.lang.OutOfMemoryError: PermGen space

The permanent generation should not be ignored, because you need enough memory allocated to it to hold all classes in all of your applications including the JSP’s. So if you have an application which uses a good number of third party libraries , has lot of files , you will definitely need a lot of Permgen space. If you are running two applications on the same server , definitely allocate some good chunk of memory to your Perm gen.

How to increase PermGen?

When you add this line in your catalina.bat or

export JAVA_OPTS=-Xms128m -Xmx192m

It only increase heap size. This is how it would look like (assuming your default PermGen is 64MB)

Increasing PermGen on tomcat

PermGen does not change
To increase PermGen , it would be

export JAVA_OPTS=-Xms128m -Xmx192m -XX:MaxPermSize=256m

See how the size of PermGen has increased.

Perm Gen increased

Perm Gen increased
This was done on Tomcat 6.0.14

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