Session session = sessionFactory.openSession();

 Transaction tx = session.beginTransaction();

 for ( int i=0; i<100000; i++ ) {

 Customer customer = new Customer(.....);

 session.save(customer);

 if ( i % 20 == 0 ) { //20, same as the JDBC batch size

 //flush a batch of inserts and release memory:

 session.flush();

 session.clear();

 }

 }

 tx.commit();

 session.close();