Hibernate: illegally attempted to associate a proxy with two open Sessions

Question

I have 2 methods:

public static Ticket issueTicket(User user,Service service,String[] seats) {
    Session ticSess= DB.factory.openSession();
    ticSess.beginTransaction();
    Date d= new Date();
    Ticket ticket=new Ticket(d, service, user);

    ticSess.save(ticket);
    ticSess.getTransaction().commit();
    int seatCount=seats.length;
    for (int i=0;i<seatCount;i++){
        int seatID=Integer.parseInt(seats[i]);
        Seat seat=getSeatByID(seatID);
        seat.setTicket(ticket);
        ticSess.update(seat);
    }
    return ticket;


}

and,

public static Seat getSeatByID(int seatID) {
    Session proSess = DB.factory.openSession();
    proSess.beginTransaction();
    Seat c = (Seat) (proSess.load(Seat.class, seatID));
    proSess.getTransaction().commit();

    return c;
}

when I call issueTicket method I get:

illegally attempted to associate a proxy with two open Sessions

and If I close the session in getSeatByID method there will be another error telling that the session is closed. Here is the Stack Trace:

at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:164)
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:285)
at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185)
at ir.ac.shirazu.cse.Terminal.Seat_$$_javassist_9.setTicket(Seat_$$_javassist_9.java)
at ir.ac.shirazu.cse.Database.DB.issueTicket(DB.java:231)

Solution

Try closing proSess in getSeatByID() before returning. Currently the Seat indeed remains attached to session opened in getSeatByID().

Comments

[Nima]

If I close the session in getSeatByID method there will be another error telling that the session is closed.

[Adam Dyga]

@Pishist Can you send full stacktrace of "closed session" exception? Maybe some lazy-initialization takes place at some point? Another thing is that I don't fully understand why you load the Seat in a separate session and transaction. You seem to open "transaction per DB operation" which is basically an anti-pattern.

[Nima]

I think if I load the Seat in the same session the problem will be solved.Thanks. What should I do instead of transaction per DB operation? I heard that the transactions won't effect the database until we close them...

[Adam Dyga]

@Pishist Read about unit of work here: docs.jboss.org/hibernate/orm/3.3/reference/en/html/…

[Gaurav]

How do you deal with concurrency then?