The comment above about making sure a transaction hasn't already started intrigues me. We're using *pessimistic* locking, but we are also using Spring's HibernateTransactionManager (specifically, annotation-based declarative transaction management). If we are not using HibernateTransactionManager to support optimistic locking, should we still be able to use HibernateTransactionManager with JBoss Cache in a clustered environment, for pessimistic locking? If JBoss Cache throws a ReplicationException, for example, shouldn't HibernateTransactionManager still roll back the transaction? Because we are seeing ReplicationExceptions and cache inconsistency, even with pessimistic locking and replication sync, I am also wondering if we are on the wrong road entirely by attempting to use JBoss Cache without JTA, even with pessimistic locking. We are running on -- Tomcat 6.0.14 -- Spring 2.0.4 -- Hibernate 3.2.5 -- JBoss Cache 1.4.1.SP9 Thanks in advance for any insights. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4155177#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...