for ( int i = 0; i < entityCount; ++i ) {
        Person Person = new Person( String.format( "Person %d", i ) );
        entityManager.persist( Person );

        if ( i > 0 && i % batchSize == 0 ) {
            //flush a batch of inserts and release memory
            entityManager.flush();
            entityManager.clear();
        }
    }

    for ( int i = 0; i < entityCount; i++ ) {
        Person Person = new Person( String.format( "Person %d", i ) );
        entityManager.persist( Person );

        if ( (i + 1) % batchSize == 0 ) {
            //flush a batch of inserts and release memory
            entityManager.flush();
            entityManager.clear();
        }
    }

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();