I repeat : none of those tools really tell you what is going on with garbage collection. They only give snapshots of current memory usage. You need to use -verbose:gc or -XX:PrintHeapAtGC, or a similar option to find out what is really going on. The JVM will eat up memory if it thinks it needs more - this has more to do with the amount of objects that survive the gc than with how much free space is available after the gc. If you want to limit its memory consumption, set the max heap to a reasonable amount. I always recommend setting min and max heap to the same size. But only after analyzing -verbose:gc data to determine the optimal heap size. Is the OOME due to the heap or the perm gen? What is the exact error message? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4145557#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...