In one of these runs (only one) I saw a ConcurrentModificationException on DiscoveryGroupImpl::listeners during a call to DiscoveryGroupImpl::callListeners. callListeners is not synchronized what would make sense. I thought it would be somehow related to this. So I made it synchronized but nothing changed on the behaviour (still have failures). View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4238883#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...