Debugging hanging website

We have a problem with an asp.net website we part build and host for a client. About a week ago the website would just failed to respond to requests, no error was returned. No code was deployed by us but the client does upload non compiled pages from time to time.

Restarting the app pool the site runs on fixes the problem but in 1-8 hours the same will happen again.

The strange thing is that the iis log shows that, while the site appears to not be responding, pages appear to be served as normal, almost as if requests are stuck in a queue or something.

The event log of the server shows nothing out of the ordinary either. The site is run on 2 servers which are load balanced using NLB. Switching the load onto one server then another shows the same results indicating that开发者_如何转开发 the issue is not environment specific but an issue with the application itself.

We have run DebugDiag with no obvious results too. We are not sure where to go with getting to the bottom of this now. Can anyone suggest some debugging techniques we could use to eliminate anything or discover the source of the issue?

Whats CPU usage like? is it maxed out (possibly maxed for the app pool if youve set a limit)?

Is it reading from a database? Is it deadlocked or otherwise stuck, preventing the pages from loading?

Just a "white page" result - so no error to the client, but no response stream either?

If so, we've had the same results with a legacy app of ours. From classic ASP to .NET 1.0, 1.1 and eventually 2.0. We forgot to terminate some "static" variables left from the original built and they became very "static" every x hours causing the app to go "white".