Iis – On Windows Server 2008, how to troubleshoot IIS hang when CPU, Disk IO are normal


Can someone recommend a good strategy for troubleshooting IIS that is hanging on Windows 2008?

Normally, I check the following in Process Explorer:

  • CPU

  • Disk I/O

  • Context Switch Delta

However, in certain situations all of these values are low and yet IIS is hung up.

Is there anything in Process Monitor (sysinternals) that should raise a red flag?

Best Answer

When IIS is not responding but it does not look like it is doing anything, it could be that it is waiting for something. The actual problem will often depend on how your application is programmed. Here are a couple of examples.

  • A system that returns a file stored in memory to many clients. If enough clients request the file you will run out of TCP connections and the system will look like it is not doing anything.
  • The application in IIS makes a call to a web service. There is a default limit of 2 http connections, so everything gets put in a queue to wait for an available connection

Check the Httperr and IIS log