ApplicationPool requires recyling spontaneously

Mathew Grabau (RR) 1

Product: IIS 8.5

We are experiencing an occasional condition where an application is getting 500 responses to an endpoint (both hosted on the same server, using separate application pools). From what I can tell, our application is not seeing the majority of requests (they are being instantly returned

When we recycle the application pool for the application (not the API), the problem seems to be fine. It's isolated to the application's application pool.

The API is ASP.NET and the application is a SPA (again, both hosted on the same server).

Are there any suggestions, debugging techniques or other information that might be relevant to isolating the problem?

Sam Wu-MSFT 7,036 Reputation points Microsoft Vendor

2021-09-09T01:44:53.75+00:00

@Mathew Grabau (RR) According to your description, I couldn’t understand your requirement clearly, applications pools allow you to separate different apps which require different levels of security and allow you to isolate your applications from one another, This way, if there is an error in one app, it won't take down other applications. Why do you want to recycle ApplicationPool spontaneously? please post more details information about your requirement.
Mathew Grabau (RR) 1 Reputation point

2021-09-09T14:39:30.407+00:00

Thanks for the reply @Sam Wu-MSFT - I really appreciate your response.

I don't want to recycle it spontaneously, I want to debug why my ApplicationPool is getting into a state where I need to restart the one application's AppPool. We currently have separate ApplicationPools, and the one the web app is running in needs to be restarted. The API one does not seem impacted, and does not have to be restarted.

I would like to know how to debug this?

I have logging on the application end, so I see a small number of errors on requests (in my API's logs, implemented in code). However, the bulk of the requests in W3C are not making it through to my API.
Sam Wu-MSFT 7,036 Reputation points Microsoft Vendor

2021-09-10T08:42:53.27+00:00

@Mathew Grabau (RR) The application pool cannot be debugged, but if you want to view the detailed request process you can use failed request tracking.