Hi S.D., 

Current JPA spec does not define any portable mechanism to obtain pessimistic locks. LockModeType.READ (or LockModeType.WRITE) are typically implemented using optimistic strategy - that is using a version column. You will have to use vendor specific features. For example here is a reference to toplink specific way to obtain a pessimistic lock. 

I know the JPA spec. doesn't define any behaviour for pessimistic locking but looking around I have read that TopLink, Hibernate and Kodo do support it.

From what I have seen the following is the appropriate way to do it and I would like to verify this.

em.lock( 
         em.getReference( x.class, x.getID() ),
         LockModeType.READ ); // Not forcing version increment.

-- do some stuff --

x = em.find( x.class, x.getID );

After doing the find I can assume that I have a serializable isolation on x?

Thanks, S.D.
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