Timeouts for long running operations…

Today I stumbled upon a timeout issue while building a web application and felt like I need to share this for those that like me wasted/are wasting hours trying to figure out why you are getting a timeout.

Here is a diagram that show the structure of the request response stack I have.

The reason why I went for an AsyncController is that the long running operation is not CPU-bound processing thus the thread that would be waiting for the response would be wasting its time waiting. More info on why and how to use Async Controllers in MVC3 can be found here.

All is fine and good until my I hit a request that took more than 1 minute, and then the nightmare of timeouts begun… So first thing I did is make sure I make the timeout for the WCF service longer. You can do this by setting the sendTimeout and the receiveTimeout of the binding in the binding configuration.

Don’t forget to do the same thing on the client side otherwise you’ll get in trouble (the config is the same as the server, and if you are using VS to generate the config then this will be done for you when you refresh the ServiceReference).

At this stage I said, wuhooo, it’s all done… but nope… it was still timing out … I was confused and puzzled… WHY WHY WHY!!!!!

Well AsyncController also have a timeout (or 90seconds as per MSDN doc), you also need to set the timeout to the async controller action in order for this to work. You do this by setting the AsyncTimeout attribute on the action that you want to extend its timeout.

With this in place all started working… but yea the errors don’t really help !

Hope this helps…