The EJB container executes exclusive control. Respective business methods and timeout methods are controlled by the Read lock or Write lock. In the case of a method for which the Read lock is set, you can concurrently execute the processing of multiple methods. In the case of a method for which the Write lock is set, any other method is not invoked until the processing of one method is complete.

Specify the type of lock for a method of the Session Bean class or overridden class with an annotation. If you do not explicitly specify the type of lock, operation is performed in the same way as when the Write lock is specified.

When executing exclusive control, you can set the timeout period for pending processes. You can specify the timeout period using the @AccessTimeout annotation. If a timeout occurs, javax.ejb.ConcurrentAccessTimeoutException is thrown for the invocation source client by an EJB container.

If you specify the Bean-Managed Concurrency, exclusive control is not executed for a Singleton Session Bean by the EJB container. Implementation related to exclusive control is required during the application development. Implement using Synchronized and volatile in the Java language depending on the purpose of usage.