One of the problems with asking questions about JON is that not everyone has it because you have to pay for it. And the trial copy I had expired many months ago and was the 1.x version anyway. In general, reaching zero free memory is not an issue. It just means that the heap is full and a garbage collection needs to take place. It also indicates to me that perhaps your young generation is not properly sized. You can read more about the heap and heap sizing at: Documentation from Sun: http://java.sun.com/docs/hotspot/gc5.0/gc_tuning_5.html A presentation I made: http://www.cecmg.de/doc/tagung_2007/agenda07/24-mai/2b3-peter-johnson/ind... View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4180670#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...