Thanks, nbelaevski for pointing out how code outside the container can't synchronize on the session, only the facade. And thanks Scott for running with this. The concern I have is StandardSession.facade is not thread safe, and what's returned from getSession() needs to be if we are going to use it as a mutex. There's no ref to facade outside StandardSession.getSession(), so ClusteredSession can override the getSession() method and replace the field with a volatile field and synchronize the construction if null. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4240095#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...