The Java EE 6 Tutorial, Volume I

RequiresNew Attribute

    If the client is running within a transaction and invokes the enterprise bean’s method, the container takes the following steps:

  1. Suspends the client’s transaction

  2. Starts a new transaction

  3. Delegates the call to the method

  4. Resumes the client’s transaction after the method completes

If the client is not associated with a transaction, the container starts a new transaction before running the method.

You should use the RequiresNew attribute when you want to ensure that the method always runs within a new transaction.