he database locking
 failure results in transaction-level rollback, the provider must
 throw the <a href="PessimisticLockException.html" title="class in javax.persistence"><code>PessimisticLockException</code></a> and ensure that the JTA
 transaction or <code>EntityTransaction</code> has been marked for rollback.
 
 <p> When the lock cannot be obtained, and the database locking
 failure results in only statement-level rollback, the provider must
 throw the <a href="LockTimeoutException.html" title="class in