A. IIS uses multiple threads to enable efficient scaling on single and multi-processor systems. By default 10 threads are used however this number can be changed but before changing you need to monitor the following items using Performance Monitor

  • Process - Thread Count - Inetinfo
  • Thread - %Processor Time - Inetino - Thread no.
  • Thread - Context Switches/sec - Inetino - Thread no.

If the IIS threads are busy nearly all the time AND the processor(s) are at maximum usage you need to consider distributing the load among other servers or adding more processors, increasing the number of threads will NOT help.

If the IIS threads are busy nearly all the time but the processor(s) are NOT at maximum usage increasing the number of threads may help.

To increase perform the following:

  1. Start the registry editor (regedit.exe)
  2. Move to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Inetinfo\Parameters
  3. From the Edit menu select New - DWORD value
  4. Enter a name of MaxPoolThreads and press Enter
  5. Double click the new value and set to between 5 and 20. Never more or less. Click OK
  6. Stop and start the IIS service