I'm using hibernate and oracle 11g2 in one of my projects. I had to upgrade recently to a new version of hibernate, first from 3.6.1 to 3.6.10 and then to 4.1.8. However after migrating to 4.1.8 now my oracle sessions are never closed even after I close SessionFactory and I don't understand why.

Below you can find an example of how I'm creating and closing the session factory:

- Using hibernate 3.6.10:
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
Session session = sessionFactory.openSession();
Journal t = (Journal) session.get(Journal.class, 12);
session.close();
sessionFactory.close();

- Using hibernate 4.1.8:
Configuration configuration = new Configuration();
configuration.configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().
applySettings(configuration.getProperties()).
buildServiceRegistry();
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.openSession();
Journal t = (Journal) session.get(Journal.class, 12);
session.close();
sessionFactory.close();

- The hibernate.cfg.xml is:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory>
<property name="hibernate.bytecode.use_reflection_optimizer">false</property>
<property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>
<property name="hibernate.connection.driver_class">oracle.jdbc.OracleDriver</property>
<property name="hibernate.connection.url">jdbc:oracle:thin:@....</property>

<property name="hibernate.default_schema">xx</property>
<property name="hibernate.connection.username">yy</property>
<property name="hibernate.connection.password">zz</property>

<property name="hibernate.show_sql">true</property>
<property name="hibernate.format_sql">true</property>
<property name="hibernate.use_sql_comments">true</property>

<mapping resource="Journal.hbm.xml" />
</session-factory>
</hibernate-configuration>

After the upgrade to 4.1.8 all oracle sessions are never closed... I usually run the following select statement to check which are the open connections:
- select status, logon_time, SID, Serial#, UserName, SchemaName, Program, Machine from v$session;

Please can anyone give me any insight on how to fix this?

Many thanks in advance.