Question

I’m facing a problem with a 3-tier application. It uses IIS and SQL Server. And the problem is that sometimes (longer requests cause higher probability) client does not receive response from IIS. It hangs when there is no activity ON SQL Server, and when even when I kill an SQL Process I get no response with an exception. When I examine data after these hangs I find that my SQL requests have succeeded, so the problem appears to be on IIS. Unfotunately I don’t have much control over the place where the application is hosted and I cannot reproduce the problem. There can be many answers to this question, but at least I need a hint in what direction I should investigate.
UPDATE: I also have an app running on the same server that does a small job: it inserts around a 100 lines line-by-line into a database. Artificially I made it run for about 10 minutes (by putting xlock on the table). After removing the xlock the process on IIS continued running and successfully inserted those 100 lines. However, control never returned to the client thereafter, it just waited indefinitely. It looks like this is a problem when returning a response to the client after a long running process.
BTW, this is not a website, but a WinForms app that uses Remoting.

Answer 1

I have finally figured out where the problem is. The application is run on a web farm and there is a balancer server between the client and IIS. There was a too small timeout on the balancer. For some reason it is not quite friendly with .net remoting and it doesn’t return any timeout exceptions to the client. The issue has been solved by increasing the timeout.