I am try to find the way to collect the Heap dump when ever I need. I have tried -xx:+HeapDumpOnOutOfMemoryError, it is creating dump during startup and application is not starting properly. We are using Jboss 4.3 and jre1.6.0_10.
If you are getting a heap dump while using that setting then you ran out of heap memory. What are your JVM options set to? The best place to look for this is in the first few lines on the console after starting the app server. You are not, by any chance, running as a Windows service???