EJB and sync

Question

Is there a Beans session (session without beans state, session with beans state)? Synced?

Answer 1

Only one thread at a time will have access to your beans. It depends on the application server. Therefore, you should not use synchronization from your beans. This is why a non-streaming, such as EntityManager, can be an instance value and not have synchronization problems.

Answer 2

Stateless Beans : Each thread / request will receive a separate EJB instance from the pool. SLB should not contain any user session data, any state. The same code can be executed in parallel. One instance is available one thread at a time.

Statefull beans are synchronized for a user session. Each user will receive their own instance of the sessions. The second thread / request will wait for the end of the first thread. Statefull EJB can store user data. One user cannot execute the same code in parallel. Different users can execute the same code in parallel.

If you are accessing a resource that does not allow concurrent access, use Singleton EJB . As the name suggests, there is only one instance. By default, access to EJB Singleton is possible from only one stream (parallelism of the managed container and @Lock (WRITE)).

Answer 3

The idle state / state segment is thread safe. Since each request will receive a dedicated bean instance, and therefore it does not need to be synchronized.

Singleton session beans are shared and must be synchronized either by the container (Container Managed Concurrency - CMC) or by the user (Bean Managed Concurrency - BMC).

Answer 4

It is very true that EJB beans is that, after creating EJB 3.0 beans, EJB methods are synchronized by default.

eg.

@Statelss Class EJBclass {

void someMethod () {}

}

now, if you do this with someMethod Synchronize, it will show an error as if it could not be synchronized at this level as it synchronizes.

EJB 3.0 beans are smart and performance is good.

Answer 5

Enterprise java beans are not synchronized. Since the beans session is supported by the ejb container, so you need to implement the application-level synchronization logic.