The 3GB option is the problem. That option allocates 3GB to apps and only 1GB to the OS. Any memory allocated by the OS (such as the memory necessary for the OS to manage a thread), comes out of that 1GB. We have found that when we use the 3GB option that it severely restricts the amount of OS resources, such as threads, that we can make use of. Unless you have some really good reasons for using the 3GB option, you should turn it off. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4141464#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...