NHibernate Session issue with NServiceBus

Question

We have a simple nservicebus (v4) setup in which a web app sends various messages to a backend endpoint for processing. Everything was going smoothly until ramping up the concurrency level. Often, but not all of the time we'll get the following exception -

System.InvalidOperationException: There is already an open DataReader associated with this Command which must be closed first.

I'm guessing this has to be an issue with the NHibernate(v3.1) Session management. Right now, we create a new session factory and session with a singleton lifecycle in each of the handlers (so each handler should have it's own session, right?). My best guess based on this exception is that the connection on the session is being used by another handler?

Can anyone shed some light? Why is this an inconsistent problem?

Append code to show the structure in how you use e.g. TransactionScope and NHibernate transactions please. — Oskar Berggren, Nov 22 '13 at 14:35

score 0 · Accepted Answer · answered Nov 22 '13 at 16:14

Found the problem. I was initializing the structuremap ObjectFactory in every handler so every new message would would overwrite what another message (on a another thread) originally initialized. This meant that all of the threads were using the session that the most recent message created. Bootstrapping in the Init() method from IWantCustomInitialization seems to have fixed the issue.

NHibernate Session issue with NServiceBus

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