Hibernate openSession() vs getCurrentSession()

If we talk about SessionFactory.openSession()

• It always creates a new Session object.
• You need to explicitly flush and close session objects.
• In single threaded environment it is slower than getCurrentSession().
• You do not need to configure any property to call this method.

And If we talk about SessionFactory.getCurrentSession()

• It creates a new Session if not exists, else uses same session which is in current hibernate context.
• You do not need to flush and close session objects, it will be automatically taken care by Hibernate internally.
• In single threaded environment it is faster than openSession().
• You need to configure additional property. "hibernate.current_session_context_class" to call getCurrentSession() method, otherwise it will throw an exception.

As explained in this forum post, 1 and 2 are related. If you set hibernate.current_session_context_class to thread and then implement something like a servlet filter that opens the session - then you can access that session anywhere else by using the SessionFactory.getCurrentSession().

SessionFactory.openSession() always opens a new session that you have to close once you are done with the operations. SessionFactory.getCurrentSession() returns a session bound to a context - you don't need to close this.

If you are using Spring or EJBs to manage transactions you can configure them to open / close sessions along with the transactions.

You should never use one session per web app - session is not a thread safe object - cannot be shared by multiple threads. You should always use "one session per request" or "one session per transaction"