Questions on Application Request Queue in IIS 6.0

Question

Question applies to IIS 6.0 and .Net 3.5

ASP.Net maintains a request queue for each AppDomain. Requests are moved to this queue if the CLR threads are busy executing.

Assumption 1: My assumption is this request queue size is derived from IIS 6.0 metabase property called "AspRequestQueueMax" which has a default value of 3000. Is this assumption correct?

The number of worker threads & IO threads that are available to execute a request and to accept incoming requests/execute callbacks can be set at Worker Process Level by using "processModel" element of IIS 6.0 metabase.

Assumption 2: There is another property called "AspProcessorThreadMax" which is applied at each Virtual Directory level and hence (assumption) at each AppDomain level.

Now if my assumption (Assumption 2) holds good then: 1. Irrespective of number of max/min worker threads configured at a Worker process level, does each domain restrict the number of CLR threads to the value configured for AspProcessorThreadMax? Or Is it that this property only applies to ASP requests and not ASP.Net?

Answer 1

The AspXXX properties are ASP specific. The size of the various request queues used by ASP.NET is configured through settings in machine.config.

Specifically, the global request queue limit is configured by the <processModel requestQueueLimit> property in machine.config. The application request queue limit is configured in Machine.config by the <httpRuntime appRequestQueueLimit> property.