November 27, 2002
Problem using HttpWebResponse with ThreadPool
I'd had similar trouble in the past trying to tune MaxIoThreads and MaxWorkerThreads. I had an ASP.NET application that was calling out to 2 or 3 Web Services, and when the system was under significant load, it would crap out - It was actually unable to get a free thread (from the system's thread pool I assume) to even get out of the box. I was getting errors in the Socket Class, in the bowels of WebRequest. [Scott Hanselman's Weblog]
It sounds like you were running into the problem using HttpWebResponse from a thread pool thread described here.