Reasons to cause OutOfMemoryError

• JVM may have a memory leak due to a bug in its internal heap management implementation. But this is highly unlikely because JVMs are well tested for this.
• The application may not have enough heap memory allocated for its running. You can allocate more JVM heap size (with –Xmx parameter to the JVM) or decrease the amount of memory your application takes to overcome this. To increase the heap space: Java -Xms1024M -Xmx1024M Care should be taken not to make the –Xmx value too large because it can slow down your application. The secret is to make the maximum heap size value the right size.
• Another not so prevalent cause is the running out of a memory area called the “perm” which sits next to the heap. All the binary code of currently running classes is archived in the “perm” area. The ‘perm’ area is important if your application or any of the third party jar files you use dynamically generate classes. For example: “perm” space is consumed when XSLT templates are dynamically compiled into classes, J2EE application servers, JasperReports, JAXB etc use Java reflection to dynamically generate classes and/or large amount of classes in your application. To increase perm space: Java -XX:PermSize=256M -XX:MaxPermSize=256M
• you may have a memory leak in your application.