java.lang.OutOfMemoryError: PermGen space in struts2 to birt integration

Hi,

We have Struts2 integrated with Birt 3.2.21 in our application. After execution of couple of reports i am facing OutOfMemoryError PermGen space issue. On the contrary if the application is accessed without using the reports the application works fine for hours.

java.lang.OutOfMemoryError: PermGen space
Exception in thread "ajp-8013-1" java.lang.NullPointerException
at java.util.concurrent.ConcurrentLinkedQueue.offer(ConcurrentLinkedQueu
e.java:190)
at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler$1.offer(Ajp
AprProtocol.java:354)
Apr 18, 2013 3:59:54 PM org.apache.catalina.startup.HostConfig undeployApps
WARNING: Error while removing context []
java.lang.OutOfMemoryError: PermGen space
at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler$1.offer(Ajp
AprProtocol.java:371)
at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler.process(Ajp
AprProtocol.java:433)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:17
03)Apr 18, 2013 3:59:59 PM org.apache.catalina.startup.HostConfig undeployApps
WARNING: Error while removing context [/manager]
java.lang.OutOfMemoryError: PermGen space


Please help me if anyone has already encountered it or have any knowledge of how to resolve it.

Regards,
Raju