Resolution:
If your engine crashes with a message like this:

06/03/09 14:49:14.125 SEVERE: while executing task: Java Calculator Example-8408893868888958695-0 java.lang.Exception: java.lang.OutOfMemoryError: Java heap space

It means that the engine jvm went out of memory. In this case it would be helpful to have a heap dump that could tell us how the memory got used. To accomplish that add the flag

-XX:+HeapDumpOnOutOfMemoryError

to your engine configuration under Engine JVM | Command-line Arguments

This will generate a file java_pid&ltpid>.hprof under ENGINE_ROOT.

    * As of this writing, the flag is available in Java 6, Java 5 update 7 and soon to be available in 1.4.2_12.
    * The flag added to the jvm command line argument does not impact performance - it is simply a flag to indicate that a heap dump should be generated when the first thread throws OutOfMemoryError.

*The .hprof file generated this way can be analyzed using a tool like jhat.

How to get JVM heap dump on engine out of memory exception