Will using Parallel.ForEach in ASP.NET prevent other threads from processing requests?

Question

I'm looking at using some PLINQ in an ASP.NET application to increase throughput on some I/O bound and computationally bound processing we have (e.g., iterating a collection to use for web service calls and calculating some geo-coordinate distances).

My question is: should I be concerned that running operations like Parallel.ForEach will take threads away from processing other requests, or does it use a separate pool of threads (I've heard about something called I/O completion ports, but not sure how that plays into the discussion)?

Answer 1

Parallel.ForEach will, at most, use one thread for as many cores as you have. The thread pool default maximum size is 250 times the number of cores you have. So you'll have to be really trying to run out of available threads.