I know that this issue has come up before on Hibernate message boards but I still haven't come across any possible solution. The problem is intermittent errors of the type:

net.sf.hibernate.HibernateException: Illegal attempt to associate a collection with two open sessions

e.g. http://www.mail-archive.com/hibernate-d ... 02239.html

in a multi-user tomcat application using Hibernate. I'm terribly worried that this is happening because of concurrent access to the same data by different requests. If so, this must be a problem that other people have encountered since it seems to be a serious impediment to the scalability of Hibernate.

So my questions are:

1. Is this a general problem and is it likely my problem or is it more likely that there is a bug in my code that forgets to close a Session?
2. What solutions have people found for limiting concurrent access to the same persisted data? I'm worried that I have to write an entire layer of logic to prevent this from happening.

Thanks for you help,

Jesse

It's not a concurrent access to persistent data.
You're trying to attach the same java instance of collection into 2 different sessions.
Are you sharing collection java instance between users ?
If you have to, implements the clone() method and use it.

So ... this is a relief ... you say it's actually the java instance of a collection being shared. So really the only way that I could be getting this bug is one of:

1. a request has more than one session and I'm accidently sharing things between them
2. something stored in the session context or application context is being shared between different concurrent sessions
3. static data is shared between two sessions

there is hope, thanks a lot