How to avoid nested transactions not supported error?

Question

I need to make sure many concurrent users be able to access the database. Although after each commit I close the session but sometimes my code runs into following error, but

Answer 1

You probably have begun a transaction, and trying to begin another one without having committed or rollbacked the previous one. The idiom when using programmatic transaction demarcation is the following one:

Transaction transaction = null;
    try {
      session = HibernateUtil.getSession();
      transaction  = session.beginTransaction();
       ...   to do ....
      transaction.commit();
    }
    catch (RuntimeException e) {
        transaction.rollback();
        throw e;
    }

Add the following property in your Hibernate.cfg.xml

 thread