LazyInitializer error

mread · **Joined:** Mon Oct 06, 2003 4:41 pm **Posts:** 18

I'm using the Open Session in View pattern and I get the following stacktrace in multi-user situations on a relatively long-lived request. I.e. it only occurs when multiple users are make requests at similar times.

My code currently doesn't implement any transaction support at all which I suspect is the cause of the error but I'd appreciate it anyone could confirm this.

Thanks,
Matt.

Code:

net.sf.hibernate.LazyInitializationException: Illegally attempted to associate a proxy with two open Sessions
        at net.sf.hibernate.proxy.LazyInitializer.setSession(LazyInitializer.java:144)
        at net.sf.hibernate.impl.SessionImpl.reassociateProxy(SessionImpl.java:883)
        at net.sf.hibernate.impl.SessionImpl.unproxyAndReassociate(SessionImpl.java:867)
        at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1259)
...

mread · **Joined:** Mon Oct 06, 2003 4:41 pm **Posts:** 18

Having read section 11.1 of the documentation again is it more likely that this error is being caused by using the class itself as the lazy initialization proxy? I'll try seperating out and using the interface instead...

Matt.

emmanuel · **Posted:** Sun Oct 19, 2003 12:42 pm

Looks like your are trying to persist the same java instance into 2 differents sessions. It isn't allowed.

Code:

myObject  = session1.load();
session2.saveOrUpdate(myObject);

It's certainly more complex than that in your case.

You can evict the object before associating it to a second session

Code:

myObject  = session1.load();
session1.evict(myObject);
session2.save(myObject);

But the best solution is not you be in such a case. Are you sharing java instance taken from session1 (still opened) and using it with a second session ?

mread · **Joined:** Mon Oct 06, 2003 4:41 pm **Posts:** 18

epbernard wrote:

Are you sharing java instance taken from session1 (still opened) and using it with a second session ?

I shouldn't be, I'm using the open session in view pattern so if my understanding is correct then each request will get a new Session instance and I'm using each session to load and save my POJOs. I guess with no transactions enabled then this is asking for trouble in a multi-user scenario. I'll let you know what happens when I start wrapping the operations in transactions.

Matt.

cutie · **Posted:** Mon Oct 20, 2003 11:51 am

Are you sure you aren't storing any persistent instance on the servlet session or application contexts, a static context, or another thread? (I'm assuming you are using Tomcat or something similar.) Session in view can cause problems if your persistent instances can exist between views, ie between HTTP requests.

mread · **Joined:** Mon Oct 06, 2003 4:41 pm **Posts:** 18

My apologies for wasting anyone's time and thanks for the help. After a fair amount of exploring I realised I was storing a reference to the Session as an instance variable in the base class for my struts actions, i.e. it wasn't threadsafe. Very stupid.

Matt.