Worker Processes

In IIS 5, applications ran in-process using the LocalSystem account by default. This account has a higher level of rights than IIS 6 worker processes do, since they run as a network service. If your application that runs just fine under IIS 5 experiences issues under IIS 6, you can check out a few of the following things.

Worker Process Identity

You can change the identity assigned to a worker process. If you want to troubleshoot application permission issues, you can assign the worker process to run under LocalSystem. This is not recommended for production use, but it is a good way to test to see whether the issues stem from the way the application interacts as a network service. If you find that the application works well as LocalSystem, you have identified the issue, and you can redesign the application around the worker processes or check permissions on a DLL to see if they are too restrictive.

Here's how to change the identity of the worker processes in an application pool:

  1. Highlight the application pool in the IIS MMC.

  2. Choose Action | Properties.

  3. Go to the Identity tab.

  4. Choose a predefined identity (Network Service, Local Service, or Local System), or select a user account from the local machine or a trusted domain.

Worker Process Recycling

Not all applications work well with worker process recycling. Most do, but some can have issues. The following four issues can cause an application to have problems running under application isolation mode:

  • Multi-instance ISAPIs that are written to be used multiple times simultaneously by different processes

  • Read raw-data filters that would try to grab all the data before it hits a web site

  • In-process session state variables, because they are lost every time a worker process is recycled

  • Applications that farm out work to their own worker processes




IIS 6(c) The Complete Reference
IIS 6: The Complete Reference
ISBN: 0072224959
EAN: 2147483647
Year: 2005
Pages: 193

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