Tuning ASP.NET thread pool

If your application queues requests with idle CPU, you should tune the thread pool.

1. For applications that serve requests quickly, consider the following settings in the Machine.config file: Set maxconnection to 12 times the number of CPUs.

Set maxIoThreads and maxWorkerThreads to 100.
Set minFreeThreads to 88 times the number of CPUs.
Set minLocalRequestFreeThreads to 76 times the number of CPUs.

2. For applications that experience burst loads (unusually high loads) between lengthy periods of idle time, consider testing your application by increasing the minWorkerThreads and minIOThreads settings.

3. For applications that make long-running calls, consider the following settings in the Machine.config file:
Set maxconnection to 12 times the number of CPUs.
Set maxIoThreads and maxWorkerThreads to 100.

4. Now test the application without changing the default setting for minFreeThreads. If you see high CPU utilization and context switching, test by reducing maxWorkerThreads or increasing minFreeThreads.

5. For ASP.NET applications that use the ASPCOMPAT flag, you should ensure that the total thread count for the worker process does not exceed the following value: 75 + ((maxWorkerThread + maxIoThreads) * #CPUs * 2)

For more information and implementation details, see :

1. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnpag/html/scalenetchapt17.asp

2. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnpag/html/scalenetchapt06.asp