30.4.3. Default Locking Behavior

Method Lock: The method lock ensures that only one thread of execution at a time can invoke on a given Entity Bean. This is required by the EJB spec.

Transaction Lock: A transaction lock ensures that only one transaction at a time has access to a give Entity Bean. This ensures the ACID properties of transactions at the application server level. Since, by default, there is only one active instance of any given Entity Bean at one time, JBoss must protect this instance from dirty reads and dirty writes. So, the default entity bean locking behavior will lock an entity bean within a transaction until it completes. This means that if any method at all is invoked on an entity bean within a transaction, no other transaction can have access to this bean until the holding transaction commits or is rolled back.