What happens if an IIS application worker process hangs?

Question

I am totally new in web programming... Now I am working on an already implemented ASP.NET MVC application which is deployed in IIS. This app is bound to an application pool which has only one worker process. At this moment, I am trying to understand what happens if the worker process freezes/hangs due to an uncontrolled exception thrown by app code. So may someone explain me it?

What we have observed is that when this happens, application stops working correctly and we need to restart its application pool in order to app begins to work correctly again. After observing this behavior, I have a doubt..... In application pool advanced configuration, under process model, the ping maximum response time (seconds) is set to 90 so as far as I know, when application pool pings the worker process and it does not respond because it is hang, after 90 seconds then worker process should terminate, but it seems it is not terminating because when this happens we need to restart application pool in order to app works again.... so Why in this case worker process does not terminate?

Answer 1

First off, you have "only" one Worker Process and should probably keep it that way. Often times Web Gardening causes more issues than it helps, particularly with .NET Apps. Second, you say it freezes/hangs due to "uncontrolled" (unhandled?) exception thrown by app code. Why do you think this is the case. Do you have an error page or something indicating its an exception? The "ping" process checks if the process is still doing work, but not necessarily finishing requests. So from the perspective of WAS, IIS is still responding.

If you want to troubleshoot, you could investigate getting a memory dump with DebugDiag and perform some automated analysis on it. https://support.microsoft.com/en-us/help/919792/how-to-use-the-debug-diagnostics-tool-to-troubleshoot-a-process-that-h