A heap dump is another important feature of the Java Virtual Machine. It contains a memory dump of all the current live Java objects of the heap.

The heap dump is useful in problematic situations, such as in a memory leak condition in a WebLogic Server where the heap usage grows until the JVM crashes by Out of Memory (OOM), or when the heap utilization is so high that the Managed Server hangs and stops responding. Both scenarios can use a heap dump to discover the offender objects in the heap.

This recipe will display how to take a heap dump from a Managed Server in the HPROF format. HPROF is a binary file that stores the heap and CPU profiles of the JVM. For demonstration purposes, the heap dump was taken from a JVM configured to a small heap with a maximum size of 256 MB (-Xmx256mb).