NHibernate, and odd "Session is Closed!" errors

Answer 1

I suggest you set a breakpoint on SessionImpl.Close / SessionImpl.Dispose and see who is calling it via the stack trace. You could also just build a debug version of NH for yourself and do the same.

HTH,
Kent

Answer 2

ASP.NET is multi-threaded so access to the ISession must be thread safe. Assuming you're using session-per-request, the easiest way to do that is to use NHibernate's built-in handling of contextual sessions.

First configure NHibernate to use the web session context class:

sessionFactory = Fluently.Configure()
    .Database(
        MsSqlConfiguration.MsSql2005.ConnectionString(p =>
            p.FromConnectionStringWithKey("QoiSqlConnection")))
    .Mappings(m => m.FluentMappings.AddFromAssemblyOf<JobMapping>())
    .ExposeConfiguration(x => x.SetProperty("current_session_context_class", "web")
    .BuildSessionFactory();

Then use the ISessionFactory.GetCurrentSession() to get an existing session, or bind a new session to the factory if none exists. Below I'm going to cut+paste my code for opening and closing a session.

    public ISession GetContextSession()
    {
        var factory = GetFactory(); // GetFactory returns an ISessionFactory in my helper class
        ISession session;
        if (CurrentSessionContext.HasBind(factory))
        {
            session = factory.GetCurrentSession();
        }
        else
        {
            session = factory.OpenSession();
            CurrentSessionContext.Bind(session);
        }
        return session;
    }

    public void EndContextSession()
    {
        var factory = GetFactory();
        var session = CurrentSessionContext.Unbind(factory);
        if (session != null && session.IsOpen)
        {
            try
            {
                if (session.Transaction != null && session.Transaction.IsActive)
                {
                    session.Transaction.Rollback();
                    throw new Exception("Rolling back uncommited NHibernate transaction.");
                }
                session.Flush();
            }
            catch (Exception ex)
            {
                log.Error("SessionKey.EndContextSession", ex);
                throw;
            }
            finally
            {
                session.Close();
                session.Dispose();
            }
        }
    }