We got a WCF service that is calling some unmanaged code. The unmanaged code is using COM and creating COM objects to do some legacy work. We noticed that when the application pool re-cycle happens (due to web.config change). The service is not always able to re-host again in a new application domain and the w3wp.exe appear to be hang. I am not getting errors or logs, except that I can't communicate to the service anymore. Killing the process and starting a new one woks. Is there a way to tell IIS not to use application domain re-cycle (due to legacy/unmanaged code in the w3wp.exe). I noticed that when using re-cycle on private bytes limit there is a process re-cycle and not a app domain recycle. What else can I do to find out the state of the w3wp.exe process and why it is hang.
I am also noticing that different recycle options create different ways to recycle. When using the UI in IIS a recycle removes the processes and put new ones. When setting a memory limit the same happens. But when changing a web config, an app domain recycle happens. Is there information to what type of re-cycle occurs based on the different trigger and is there ways to configure it?
