multithreading - How is ASP.NET multithreaded?

Question

I've been told that ASP.NET is multithreaded by default in IIS. How is this threading achieved?

Does the server farm send different requests to different cores?

Does a single request make use of multiple cores?

More importantly, are there any advantages to adding threads to ASP.NET code if the threading is done higher up in IIS?

Answer 1

Not only does the server farm different requests to different threads, but a single request can change thread during the course of life cycle. This is called thread agility. I'm looking for a good article explaining it...

EDIT: No definitive articles yet, but one blog post explaining some of the difficulties.

EDIT: More links from comments:

• ASP.NET Thread Switching (blog post)
• What is an "async IO operation" in .NET? (SO question; sounds irrelevant but isn't)
• ASP.NET and System.Diagnostics tracing (SO question)
• Threading differences between IIS 6 and 7