I'm fitting hibernate into an existing webapp, and I'm forced to use a long-lived hibernate session (that is stored in the http session) that I flush and disconnect at the end of each http request:



The thing I'm worried about is the thread safety of the hibernate session object. (ie. simultaneous http requests from the same user that come in on different threads)

I can easily put a sync block around the code that explictly references the session object, but is that enough? Is the session object also used when an object is modified, or lazy fetching occurs?

-Trevor

You surely misuse Hibernate but it depends on what you want to accomplish. Maybe the "Open Session In View" pattern is what you want to use.

But for your specific question, lazily loading an object implies it's bound to a session, otherwise you'll have an exception (it's a normal behaviour : if the object is not bound to a session, it means that it's not under hibernate's control, thus you cannot fetch anything more than what has been fetched before).

The case of the "modified object" results in a misunderstanding. You can modify your object either if it's bound with a session or not. But the results will then vary. If it's bound to a session, the object is again under the control of hibernate, and hibernate will reflect the changes - depending on mapping. If it's not bound to a session, you'll lose synchronization with database due to the fact that you changed your object and didn't notice hibernate about it.

I hope it helps.

Yes, I realize that I'm not using the best hibernate pattern, but it is one that is discussed quite a bit in the docs.


I'm not seeing any information regarding the thread safety of a session in your reply. Maybe I'm dense.

I'm aware that I need to have an object bound to a session before anything can happen. I'm using session-per-conversation, where the session isn't closed between requests... the transaction is just committed and a new one is started for the next request.

From the hibernate manual, section 11.1.4:



As in my original post, I'm wondering if the hibernate session object gets involved even when not explictly referenced, ie. by modifying an object, or accessing an object's property that causes some lazy loading to occur.

The paragraph from the manual just suggests taking a shotgun to the problem. I'm wondering if I can be a little more fine grained about it.

-Trevor