nHibernate session and multithreading

Question

I had a method with a lot of persistence calls that used a nHibernate session, it worked, was alright. But I needed to refactor this method, extracting a method from a content inside a loop, for multithread reasons. Then I created an class with this method. It is like a normal refactoring, but the nHibernate session inside this method call is broken, without context, I didn't finalize it at any moment. Has nHibernate problems with multithreading? Even when I have only one more thread executing, I have the same problem.

I use nHibernate Session through a SessionFactory and Façade pattern, it means, the session is not a field of these objects, it is global at SessionFactory.

---

Making it a little bit more clear:

BEFORE:

Method()
{
... persistence calls
foreach(Thing..)
{
...persistence calls for each thing (1)
}
...
}

AFTER:

Method()
{
... persistence calls
foreach(Thing..)
{
create a thingResolver object with some data
open a new thread with thingResolver.Method (1)
starts this thread
}
.. waits for finishing threads and continues
}

---

Our nHibernate Session Factory is thread-aware, and stores/retrieves nHibernate session per thread. It is working nicely now ;)

Answer 1

Sessions are not thread safe in NHibernate by design. So it should be ok as long as you have a session used by only one thread.

I'm not sure what you're thingResolver does, but if it does some persistance calls on the same session you've created in the originating thread - this most probably the cause of your problems, you could create a separate session in your new thread so that it would be a session per thread if my assumption is true.

NHibernate reference has it in section 10.2

http://nhibernate.info/doc/nh/en/index.html#transactions