When I add @Async, entityManager.flush() will raise an exception

Question

I\'m using Spring framework.

The structure of my project is Controller ➡️ Service ➡️ Logic.

I added @Transactional in Logic cla

Answer 1

I think this is a bug.

• With No @Async
  • When request comes, TransactionSynchronizationManager.bindResource((Object key, Object value) will be called, and a new EntityManager will be bound to current thread.
  • Then, EntityManagerFactoryUtils.doGetTransactionalEntityManager(EntityManagerFactory emf, @Nullable Map<?, ?> properties, boolean synchronizedWithTransaction) is called to get the bound EntityManager. Inside this method, it will call EntityManager.joinTransaction(). This method will call JdbcResourceLocalTransactionCoordinatorImpl.getTransactionDriverControl() to initialize TransactionDriverControlImpl physicalTransactionDelegate.
  • When we call EntityManager.flush(). JdbcResourceLocalTransactionCoordinatorImpl.isJoined()will be called to check.
• With @Async
  • When request comes, TransactionSynchronizationManager.bindResource((Object key, Object value) will be called, and a new EntityManager will be bound to current thread.
  • If there is a @Async, a new thread will be created.
  • Then, EntityManagerFactoryUtils.doGetTransactionalEntityManager(EntityManagerFactory emf, @Nullable Map<?, ?> properties, boolean synchronizedWithTransaction) is called to get the bound EntityManager. But in this new thread, there is no bound EntityManager, so a new one will be created, but EntityManager.joinTransaction() will not be called. So TransactionDriverControlImpl physicalTransactionDelegate will not be initialized.
  • When we call EntityManager.flush(). Since TransactionDriverControlImpl physicalTransactionDelegate is null, an exception will be raised.

Why EntityManager.joinTransaction() is not called when a new EntityManager is created in a new thread?

Answer 2

I found the solution. Just add entityManager.joinTransaction();.