Steve, I missed you ping yesterday about HHH-9857. I reworked based on the EntityEntry needing to be threadsafe to be shared across sessions. With the current impl a new EntityEntry is created for each PeristenceContext. If we share it between sessions, there is a race condition on the compressedState field, as multiple threads will access the same object. We had discussed about making access to this field threadsafe, or removing some of the operations and making the ImmutableEntityEntry objects immutable themselves. I have used a ReadWriteRentrantLock in ImmutableEntityEntry to remove the race cond. as this appeared to require least code change, but I am uncertain atm what impact this will have on performance as it is in a critical section of code. I have not been able to test my changes as we currently have an issue with our perf lab after a recent upgrade. I will test as soon as I can to see what impact this has on cpu. This change only impacts ImmutableEntityEntry, and not MutableEntityEntry Thanks John -- John O'Hara johara(a)redhat.com JBoss, by Red Hat Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in UK and Wales under Company Registration No. 3798903 Directors: Michael Cunningham (USA), Charlie Peters (USA), Matt Parsons (USA) and Michael O'Neill (Ireland).