Hibernate: cleaning up sessions

Question

Suppose I have the following:

public class DAOFactory {
    @Inject private final SessionFactory factory;
    private final ThreadLocal<Session> session = new ThreadLocal<>();

    // In a nutshell: create an AbstractDAO associated with the session object held by the ThreadLocal above
    public <T> AbstractDAO<T> createObject(Class<T> objectClass) { ... }
}

The problem that I have is that these sessions need to be closed, and only the thread creating the DAO from createObject() can do that. Clearly, AbstractDAO cannot have a close routine, since the same Session can be associated with multiple AbstractDAO objects, so DAOFactory has to shoulder the burden of closing sessions. Still, there is a risk of dangling Session s: if the thread creating the AbstractDAO no longer exists, how can the associated Session be closed?

One approach I have is to have a cleanup method as follows:

public class DAOFactory {
    // createObject() uses Thread.getCurrentThread.getId() and sessionMap.computeIfAbsent()
    private final ConcurrentMap<Long, Session> sessionMap = new ConcurrentHashMap<>();

    public void cleanup() {
        for (Session session : sessionMap.values()) {
            session.close();
        }
        sessionMap.clear();
    }
}

The question is "how safe is this approach", "is this a good idea", and "should this be done"? If not, what's a good alternative?

Note that DAOFactory is largely created with some kind of testing situation in mind: one thread starts a test run and creates a DAOFactory , and it may spawn other threads that uses it. The thread creating DAOFactory will always outlast any threads that it spawns, and will always be the one calling cleanup() at the end of a test.

Answer 1

Manual Session management is not a good idea. Hibernate already offers a SPI, so that you don't have to do it yourself.

I suggest you start using Spring transaction management, which also offers automatic session management as well.