How to be sure entity is persisted before calling another thread which queries this persisted entity?

Question

I have the following situation in my Java web app (Spring + JPA):

1. I have method which persist an entity to the database
2. Right after persist entity, I call notify() which is waking up another thread.
3. The second thread is working with the entity i've just persisted.

So as a result I have: Second thread queries a new-persisted entity, but it is not there yet. So second thread sends query to the database faster then main thread persist it. If i add some timeout it works perfectly. But it is not a suitable solution for me. I guess I can check entitymanager with contains() method. But I am not sure how efficient it will be. I am quite new in this subject, so I would be glad to hear your advices.

p.s. I am using Spring framework, so persist and notify happend in one transaction (marked with @Transactional annotation). second thread does not have any @Transactional classes.

Thanks, Emily.

Answer 1

Real persist to the database happens only after commit of the transaction, as far it happens in @Transactional method . So I needed to call second thread after transaction commit and I was able to do it using TransactionSynchronizationManager and its afterCommit() method. Here is the link with all info and examples http://azagorneanu.blogspot.ru/2013/06/transaction-synchronization-callbacks.html Maybe it will be useful for somebody.

Answer 2

Try using the Entity Listeners for being notified when an entity is persisted. You can read about entity listeners in the JPA Wiki Book, the Hibernate documentation and at www.objectdb.com.