Hibernate session management

Question

I'm using hibernate and have some trouble in how to use session, which is best method :

1. use one session and open it in singleton

   public static CommonServiceImpl getInstance() {
   
       if (session == null ||  !session.isOpen() ) {
           session = sessionFactory.openSession();
       }
       //session.clear();
       return instance;
   }
   

2. Use SessionFactory each time when i wanna use the session with sessionFactory.getCurrentSession() ?

Answer 1

The session object is designed to be a lightweight, disposable object that you can open and dispose on demand.. You should not try to reuse it on your own (like singleton)
The real problem is thread safety: while the SessionFactory object is thread safe, the session object is not and will cause havoc when pointed from several threads.
If you don't want to open a new session every time you can use the current session option which allows you to bind a session to a specific context (like a thread) within the session factory and then retrieve it each time..