Salvar lista de Objetos - Hibernate

public void insertLista(ArrayList obj) throws PersistenceException {
		
		Session session = getSession();
		try {
			Iterator i = obj.iterator();
			int in = 0;
			
			session.beginTransaction();
			
			while(i.hasNext()){
				
				Object ent = new Object();				
				ent = i.next();
				
				session.saveOrUpdate(ent);
				in++;
				if(in % 20 == 0 ){
					session.flush();
					session.clear();
				}
			}
			
			if (persiste) session.beginTransaction().commit();
		} catch (HibernateException e) {
			logger.error(e);
			throw new PersistenceException(e);
		} finally {
			closeSession();
		}
	}