How to handle opening and closing Hibernate sessions

AgentQueue.java

Session session = HibernateUtil.getSessionFactory().openSession();
session.setFlushMode(FlushMode.MANUAL);
ManagedSessionContext.bind(session);
session.beginTransaction();
		
Query getAgentsQuery = session.createQuery(" from AgentModel where active=true");
@SuppressWarnings("unchecked")
List<AgentModel> agentList = getAgentsQuery.list();

for (AgentModel agentModel : agentList) {
		
	log.info("Instantiating agent " + agentModel.getName() + " using class: " + agentModel.getClassName());

	AbstractApplicationContext agentContext = new ClassPathXmlApplicationContext("agents-context.xml");
  Agent agent = (Agent) agentContext.getBean(agentModel.getClassName());
			
			if (runThreaded.equals("true"))
				agent.start();
			else
				agent.run();
			
			agentContext.registerShutdownHook();
			agentContext.close();
			
		}
		
		ManagedSessionContext.unbind(HibernateUtil.getSessionFactory());
		session.flush();
		session.getTransaction().commit();
		session.close();