Postgres is leaving too many open sessions

crodv · **Joined:** Tue Jul 15, 2008 11:09 pm **Posts:** 2

Hi all,

I'm a beginner in hibernate and I am working with Postgres, my problem is that aparently hibernate is leaving a lot of open sessions to Postgres. I realized that when I went to Postgres Pgadmin-tools-server status, this is showing me a lot of PID all of them with Query=<IDLE>.

The way I'm using hibernate is basically:

SessionFactory sessionFactory = ht.getSessionFactory();
Session session = sessionFactory.openSession();
session.beginTransaction();
Query query = session.createQuery("from TABLE where id = XXX");
myResult = query.list();
session.getTransaction().commit();
session.disconnect();
session.close();

Any help would be great.

Cameron McKenzie · **Posted:** Wed Jul 16, 2008 6:10 am

You definitely don't want to be creating quite so many SessionFactory objects, that's for sure.

The other thing I'd say is that you probably want getSession, not openSession. There's a big difference! getSession is typically the right choice, unless you want to manage the state of the session yourself.

I've got a good tutorial on using the HibernateUtil class. You might want to create one of your own and use it:

http://www.hiberbook.com/HiberBookWeb/learn.jsp?tutorial=05samplehibernateutilclassexample

Code:

package com.examscam;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import com.examscam.model.User;

public class HibernateUtil {

 private static SessionFactory factory;

 public static Configuration  
             getInitializedConfiguration() {
   AnnotationConfiguration config = 
               new AnnotationConfiguration();
/* add all of your JPA annotated classes here!!! */
   config.addAnnotatedClass(User.class);
   config.configure();
   return config;
 }

 public static Session getSession() {
   if (factory == null) {
   Configuration config =  
      HibernateUtil.getInitializedConfiguration();
   factory = config.buildSessionFactory();
   }
   Session hibernateSession = 
                   factory.getCurrentSession();
   return hibernateSession;
 }

 public static void closeSession() {
   HibernateUtil.getSession().close();
 }


 public static void recreateDatabase() {
   Configuration config;
   config = 
       HibernateUtil.getInitializedConfiguration();
   new SchemaExport(config).create(true, true);
 }

 public static Session beginTransaction() {
   Session hibernateSession;
   hibernateSession = HibernateUtil.getSession();
   hibernateSession.beginTransaction();
   return hibernateSession;
 }

 public static void commitTransaction() {
   HibernateUtil.getSession()
                .getTransaction().commit();
 }

 public static void rollbackTransaction() {
   HibernateUtil.getSession()
                 .getTransaction().rollback();
 }

  public static void main(String args[]) {
    HibernateUtil.recreateDatabase();
  }

}

http://www.thebookonhibernate.com/HiberBookWeb/learn.jsp?tutorial=05samplehibernateutilclassexample

You might also want to look at this quick tutorial on How Hibernate Works to get a better understanding of what's going on in your code:

http://jpa.ezhibernate.com/Javacode/learn.jsp?tutorial=07howhibernateworks

crodv · **Joined:** Tue Jul 15, 2008 11:09 pm **Posts:** 2

Really makes sense your suggestion, I will try that, I guess that you mean method getCurrentSession().

I'll let you know how it goes.

Thanks!

BTW: We ordered your hibernate book!

Cameron McKenzie · **Posted:** Fri Jul 25, 2008 3:00 am

Fantastic! Thanks for the order. :) Make sure you get Bauer and Kings book too. It's the reference.

And yes, getCurrentSession can make all the difference!

-Cameron McKenzie