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Currently, my IIS log entries are written when each request completes, eg:

2012-02-15 00:31:50 W3SVC1 MACHINENAME ::1 POST ... 202 (milliseconds)

Unfortunately, sometimes requests hang or don't result in a response, due to bugs in the ASP.NET code. These don't get included in that log. I know I can probably use Failed Request Tracing for some of these scenarios, but it would be good to have these requests shown in the standard IIS log as well.

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The ones that don't end up in the W3SVC log should end up in the HTTPERR log (\Windows\System32\LogFiles) with the reason for failure.

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+1 as this is a useful point, but I've found this does not include requests which hang. – Jon Mar 15 '12 at 6:20
HTTP.SYS tracks requests from the point at which they're received to the point at which the App Pool abandons them. If requests hang forever, they'll be logged when the App Pool terminates, worst case, unless there's a bug there. If requests hang, use a hang dump and DebugDiag to work out why. – TristanK Mar 15 '12 at 19:41
That's true, but it means you have to terminate the App Pool to see the hung requests logged. – Jon Mar 16 '12 at 4:11
Yes, but... one would suggest is that the right approach is to focus on why they're hanging, not that they need to be logged. If you got to the Worker Processes view at the Server level of IIS manager, you can see the requests that are piled up in each... but dumping the request and analysing the reason for the problem is probably more productive than merely logging them. Which will happen eventually. – TristanK Mar 16 '12 at 8:27

The short answer is: No, you can't modify the default logging behavior of HTTP.sys in Windows.

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Do you have a link which proves this? – Jon Mar 14 '12 at 7:25

IIS is not the place to log this. If you are debugging your ASP.NET application, then you need to add hooks into it to get you the data and eventual informatics you need.

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If there's a delay between the request coming into IIS and arriving at the ASP.NET layer, I want to see this. The entry point at the ASP.NET layer is too late to log this. – Jon Mar 15 '12 at 1:14

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