Use of Asynchronous Threading in ASP.Net

Jasper Lee and I did some work a while back on threading. It proved to be funf and some important lessons were learnt on appropriate use of aysnchronous threading. Specifically how to avoid HTTP 503 errors ("The service is temporarily overloaded")

Improving web services performance by Microsoft Patterns & Practices group

Do Not Use Asynchronous Web Methods When You Depend on Worker Threads

Processing Long Running Tasks With Asynchronous Handlers and XMLHTTP

Use Threads and Build Asynchronous Handlers in Your Server-Side Web Code by Fritz Onion.

.NET Application Performance

Avoid polling for asynchronous invocation results. Polling is inefficient and uses precious processor cycles which can be used by other server threads.

On the other hand

A common approach to handling long-running calls is to have the client poll for results

How To: Submit and Poll for Long-Running Tasks

Of course if I was a bit more with it I would be using Ajax or even Atlas