couzteau wrote : I'm guessing that a garbage collector thread crashed. I doubt that a thread crashed - the JVM would have taken a dump if it did. But I would guess that you are hitting a major garbage collection. A major collection on a 2GB heap will take a long time, and with a parallel collector you will see 100% CPU usage (and a lot of that usage will be kernel time). See my presentation for ideas on how to determine if the problem really is garbage collection related and how you could go about tuning it. http://www.cecmg.de/doc/tagung_2007/agenda07/24-mai/2b3-peter-johnson/ind... Another thing you could do - when this slowdown hits, take a JVM thread dump and look at which threads are running and what they are doing. If it is not the CG threads running, then take several thread dumps a few seconds apart - this will help you identify code that could be causing a problem. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4173167#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...