ConcurrencyMode Property

CallbackBehaviorAttribute.ConcurrencyMode Property

Gets or sets whether a service supports one thread, multiple threads, or reentrant calls.

Namespace:  System.ServiceModel
Assembly:  System.ServiceModel (in System.ServiceModel.dll)

public ConcurrencyMode ConcurrencyMode { get; set; }

Property Value

Type: System.ServiceModel.ConcurrencyMode
One of the ConcurrencyMode values; the default is Single.


The value is not one of the ConcurrencyMode values.

This property indicates whether an instance of a callback object supports one thread or multiple threads that execute concurrently, and if single-threaded, whether reentrancy is supported.

Setting ConcurrencyMode to Single instructs the system to restrict instances of the service to one thread of execution at a time, which frees you from dealing with threading issues. This is the default value. A value of Multiple means that service objects can be executed by multiple threads at any one time. In this case, you must ensure thread safety and state consistency.

Reentrantalso restricts access to a single thread at a time. However, it enables calls out from an executing service method to return and reenter the executing service. A reentrant call can execute on a different managed thread, but in this case the original thread is blocked for the duration of the reentrant call.

Generally, if a message arrives for an instance that violates its concurrency mode, the message waits until the instance is available, or until it times out.

In addition, if the ConcurrencyMode is set to Single and a reentrant call is blocked while waiting for the instance to be freed, the system detects the deadlock and throws an exception.

For more information about concurrency, see ServiceBehaviorAttribute.ConcurrencyMode and Sessions, Instancing, and Concurrency.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

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

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