topic Re: What is IIS modules as the root cause? in Open Q&A

What is IIS modules as the root cause?

dparkar — Tue, 27 Apr 2021 12:07:18 GMT

Trying to find the root cause of a response degradation.

DynaTrace shows that top findings as IIS Modules.

Time consumed by IIS modules is equal to response time of the degraded response.

Further clicking on IIS modules there is a breakdown which says 'General' (100%)

Re: What is IIS modules as the root cause?

skrystosik — Tue, 30 Apr 2019 10:27:55 GMT

Did you turned on on host (edit settings) beta support for IIS modules? Than you will see list of those modules with response time contribution. In General IIS is webServer, it uses modules to handle session, transactions routing etc. Sometime those modules has issues.

Sebastian

Re: What is IIS modules as the root cause?

dparkar — Tue, 30 Apr 2019 10:29:52 GMT

Yes that is turned on.

Re: What is IIS modules as the root cause?

dparkar — Tue, 30 Apr 2019 10:33:24 GMT

There is a long list of modules under IIS modules on the view response time hotspots page.

Out of which it says 'General' is contributing 100% to the response degradation.

Re: What is IIS modules as the root cause?

skrystosik — Tue, 30 Apr 2019 10:50:56 GMT

To analyse it you can check perfview to record session or debugdiag. Both are tools from microsoft. As well you can start performance monitor and check amount of requests on iis, if some of them are waiting. Maybe resources of this IIS are exhausted. Configuration is default or custom? IIS is hard to analyse, such cases needs experts from IIS. DT will not show you more.

Sebastian

Re: What is IIS modules as the root cause?

dparkar — Tue, 30 Apr 2019 12:32:52 GMT

Thanks 🙂

Re: What is IIS modules as the root cause?

Julius_Loman — Tue, 16 Jul 2019 13:26:53 GMT

From my experience, a high "General" IIS module usage means the client is consuming response slowly. (Client typically has slow network connection). Thus it is not a problem of the application or IIS.

Re: What is IIS modules as the root cause?

skrystosik — Tue, 16 Jul 2019 19:53:23 GMT

Can you say something more about it? I’ve got situations like this with couple of minutes spent on general iis module, this was during loadtests where internet connection was just fine. I’m curious about correlation here. Are you suggesting that for example iis is serving 1mb payload which is downloaded by client for some time?

From my experience with iis there aren’t only one explenation for the same symptoms. I rather prefer java applications or at least .net core for analysis 🙂

Sebastian

Re: What is IIS modules as the root cause?

Julius_Loman — Wed, 17 Jul 2019 07:00:43 GMT

I agree, it's difficult to debug and this is not the only single explanation. However, I've done some testing and this slow network (large http responses with the combination of slow or laggy connection lead to this outcome).

Re: What is IIS modules as the root cause?

skrystosik — Wed, 17 Jul 2019 07:06:52 GMT

Good to know for the future 🙂 I'll check this clue when I will have such issue next time