JVM arguments

Java™ virtual machine (JVM) arguments are defined in the startup command script (Oracle WebLogic) or Admin Console (IBM® WebSphere®) for your web application server.

Confirm you have the latest service packs and patches installed for your operating system, web application server, and JVM.

For best performance, when using Sun HotSpot VM, use the –server argument.

Decide on a maximum heap size for the JVM, based on the memory availability in the server. (Interact is not a memory intensive application). Set the max and min sizes of the heap to be the same (using –Xmx and -Xms arguments), which increases the startup time, but gives better throughput.

If the application is unresponsive periodically, for example, long response times running to few seconds, the Garbage Collection policy might need to be tuned. Monitor Garbage Collection runs using JMX console and by studying the Garbage Collection output after enabling the following arguments.

-verbosegc -XX:+PrintGCDetails

In our tests, the Low Pause Collector was found to eliminate Garbage Collection-related slowness without sacrificing throughput. The following is one set of options was found to be useful for a 2 GB JVM heap.

-XX:+UseConcMarkSweepGC -Xmn512m -XX:SurvivorRatio=6

In general, the young collection should be about 1/4 to 1/2 of the total heap. The Survivor Space can be set to 1/8th the size of young collection.

References

Tuning Garbage Collection with the 5.0 Java™ virtual machine (http://java.sun.com/docs/hotspot/gc5.0/gc_tuning_5.html)

Java™ Tuning white paper (http://java.sun.com/performance/reference/whitepapers/tuning.html)