Close SessionFactory in Hibernate 4.3

Question

I'm upgrading my Hibernate to the latest version. With my old HibernateUtil.java I had no problems but when upgrading it, the SessionFactory doesn't seem to close anymore.

This is my new HibernateUtil.java class:

import org.hibernate.HibernateException;
import org.hibernate.cfg.Configuration;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;

public class HibernateUtil {

    private static final SessionFactory sessionFactory;

    static {
        try {
            Configuration configuration = new Configuration().configure();
            StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties());
            sessionFactory = configuration.buildSessionFactory(builder.build());
        } catch (HibernateException ex) {
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public static void closeSessionFactory() {
        sessionFactory.close();
    }
}

This is my old HibernateUtil.java class:

import org.hibernate.cfg.Configuration;
import org.hibernate.SessionFactory;

public class HibernateUtil {

    private static final SessionFactory sessionFactory;

    static {
        try {
            // Create the SessionFactory from standard (hibernate.cfg.xml) 
            // config file.
            sessionFactory = new Configuration().configure().buildSessionFactory();
        } catch (Throwable ex) {
            // Log the exception. 
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public static void closeSessionFactory() {
        sessionFactory.close();
    }
}

This is my hibernate.cfg.xml:

<?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>
        <!-- Database connection settings -->
        <property name="hibernate.dialect">org.hibernate.dialect.H2Dialect</property>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mydatabase</property>
        <property name="hibernate.connection.username">user</property>
        <property name="hibernate.connection.password">pass</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.H2Dialect</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">false</property>
        <property name="format_sql">false</property>
        <property name="use_sql_comments">false</property>


        <!-- Use the thread as the context -->
        <property name="hibernate.current_session_context_class">thread</property>

        <!-- Use these files for mapping configuration -->
        <mapping resource="test/Person.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

Code in which I create the session:

public class Helper {

    Session session = null;

    public Helper() {
        this.session = HibernateUtil.getSessionFactory().getCurrentSession();
    }

    public List getPeople(int id) {
       ...
    }
}

Main method:

public static void main(String args[]) {
    Logger log = Logger.getLogger("org.hibernate");
    log.setLevel(Level.WARNING);

    Helper helper = new Helper();
    List<Person> people = helper.getPeople(1);

    for (int i = 0; i < people.size(); i++) {
        System.out.println("people " + i + ": " + people.get(i).getID());
    }

    HibernateUtil.closeSessionFactory();
}

Answer 1

You're right, there appears to be a bug in Hibernate 4.3.x in which a thread spawned by Hibernate's default connection pool doesn't get cleaned up on shutdown. I filed a bug here (please vote!):

https://hibernate.atlassian.net/browse/HHH-8896

Until it's fixed, you have two choices. You can add a method to your HibernateUtil and use it to force the connection pool to clean itself up at the end of your app's execution:

public static void stopConnectionProvider() {
    final SessionFactoryImplementor sessionFactoryImplementor = (SessionFactoryImplementor) sessionFactory;
    ConnectionProvider connectionProvider = sessionFactoryImplementor.getConnectionProvider();
    if (Stoppable.class.isInstance(connectionProvider)) {
        ((Stoppable) connectionProvider).stop();
    }        
}

This works, but it's ugly, hacky, uses a deprecated method, etc. The better solution would be to just use a "real" connection pool, like c3p0, which can be enabled just by adding the following properties to your hibernate.cfg.xml:

<property name="hibernate.c3p0.acquire_increment">1</property>
<property name="hibernate.c3p0.idle_test_period">100</property>
<property name="hibernate.c3p0.max_size">10</property>
<property name="hibernate.c3p0.max_statements">10</property>
<property name="hibernate.c3p0.min_size">10</property>
<property name="hibernate.c3p0.timeout">100</property>

Note that if you use another connection pool, you should remove this connection pool property which is currently in your config:

<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>

Edit: to use c3p0 connection pooling you'll also need the hibernate-c3p0 dependency. Maven example for 4.3.0-SNAPSHOT from the Hibernate snapshots repo:

<repositories>
  ...
  <repository>
    <id>hibernate-snapshots</id>
    <url>http://snapshots.jboss.org/maven2/</url>
  </repository>
  ...
</repositories>

<dependencies>
 ...
 <dependency>
   <groupId>org.hibernate</groupId>
   <artifactId>hibernate-c3p0</artifactId>
   <version>4.3.0-SNAPSHOT</version>
 </dependency>
 ...
<dependencies>

Answer 2

The issue seems to be already solved in Hibernate version 4.3.5 .

sessionFactory.close();

works in my program.