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ProcessModelSection.MaxWorkerThreads Property

Gets or sets a value indicating the maximum amount of worker threads per CPU in the CLR thread pool.

Namespace:  System.Web.Configuration
Assembly:  System.Web (in System.Web.dll)

[ConfigurationPropertyAttribute("maxWorkerThreads", DefaultValue = )]
[IntegerValidatorAttribute(MinValue = , MaxValue = )]
public int MaxWorkerThreads { get; set; }

Property Value

Type: System.Int32
The maximum number of threads. The default is 20.

The value of MaxWorkerThreads must be equal to or greater than the MinFreeThreads setting in the httpRuntime configuration section.

You can have some control over the CPU utilization by setting the number of worker threads and I/O threads, using the MaxWorkerThreads property and, the MaxIOThreads property, respectively.

The difference between the two types of threads is that the latter are bound to I/O objects, such as a stream or a pipe, and the former are traditional unrestricted threads. For Internet Information Services (IIS) version 6.0 and higher, ASP.NET processes requests on worker threads. This is because ASP.NET is integrated within IIS.

These threads are obtained from the process-wide CLR thread pool belonging to an application.


Usually the default values for the allowed threads are sufficient to keep the CPU utilization high. If for some reason your application is slow, perhaps waiting for external resources, you could try to increase the number of threads to a value less than 100.

The following code example shows how to access the MaxWorkerThreads property.

// Get the current MaxWorkerThreads property value. 
int maxWorkerThreads = 

// Set the MaxWorkerThreads property to 128.
processModelSection.MaxWorkerThreads = 128;

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0