I (or you or nbelaevski if either is up for it) need to review the session replication code to see how much of an issue this is. I haven't had cycles to do that, which is why my comments here are vague. If the issue is only protecting the attributes, then synching on the facade in the places where we serialize it is fine. If something broader is needed, the best way to decide what to do is the perf test the two approaches. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4241548#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...