I just now tried this on my Linux desktop at home and I saw all 4 CPUs in use. What Linux distro are you running? How are you verifying that only 2CPUs are in use? With JBossAS running, get the PID for it (you can find it via "ps -ef | grep java") and post the result from running this command (replacing 9999 with the PID for JBossAS): taskset -p 9999 If taskset indicates that the java process is affinitized to more than 2 CPUs, then kjkoster is correct in asserting that there is something about your app that is prevent proper parallelization. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4171836#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...