Sync's are not persisted, so don't get called at all in a recovery scenario if the JVM containing them crashed. In non-crash cases they should be called exactly once. In looking at the code, the collection used to hold the set of Syncs registered for a particular tranaction is explicitly nulled out in the end of afterCompletion processing. However, there is another reference to just one Sync (the last one processed in beforeCompletion) that is not nulled. It therefore won't be colleced until the containing transaction is, although that should not be a problem. I'll add code to explicitly null it out anyhow. Jonathan View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4028040#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...