Have a look at this thread:
http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4218569
Does it make sense to enforce READ_COMMITTED for the Hibernate 2nd
Level Cache provider for JBC3, if MVCC is used?
Cheers
--
Manik Surtani
Lead, JBoss Cache
http://www.jbosscache.org
manik(a)jboss.org