ServiceThrottlingBehavior.MaxConcurrentInstances Property

Definition

Namespace:

System.ServiceModel.Description

Assembly:

System.ServiceModel.dll

Gets or sets a value that specifies the maximum number of InstanceContext objects in the service that can execute at one time.

public:
 property int MaxConcurrentInstances { int get(); void set(int value); };

public int MaxConcurrentInstances { get; set; }

member this.MaxConcurrentInstances : int with get, set

Public Property MaxConcurrentInstances As Integer

Property Value

Int32

The maximum number of InstanceContext objects in the service at one time. The default is the sum of the value of MaxConcurrentSessions and the value of MaxConcurrentCalls.

Examples

The following code example shows the use of ServiceThrottlingBehavior from an application configuration file that sets the MaxConcurrentSessions, MaxConcurrentCalls and MaxConcurrentInstances properties to 1 as an example. Real-world experience determines what the optimal settings are for any particular application.

<configuration>
  <appSettings>
    <!-- use appSetting to configure base address provided by host -->
    <add key="baseAddress" value="http://localhost:8080/ServiceMetadata" />
  </appSettings>
  <system.serviceModel>
    <services>
      <service 
        name="Microsoft.WCF.Documentation.SampleService"
        behaviorConfiguration="Throttled" >
        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:8080/SampleService"/>
          </baseAddresses>
        </host>
        <endpoint
          address=""
          binding="wsHttpBinding"
          contract="Microsoft.WCF.Documentation.ISampleService"
         />
        <endpoint
          address="mex"
          binding="mexHttpBinding"
          contract="IMetadataExchange"
         />
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior  name="Throttled">
          <serviceThrottling 
            maxConcurrentCalls="1" 
            maxConcurrentSessions="1" 
            maxConcurrentInstances="1"
          />
          <serviceMetadata 
            httpGetEnabled="true" 
            httpGetUrl=""
          />
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>
</configuration>

Remarks

The MaxConcurrentInstances property specifies the maximum number of InstanceContext objects in the service. It is important to keep in mind the relationship between the MaxConcurrentInstances property and the InstanceContextMode property. If InstanceContextMode is PerSession, the resulting value is the total number of sessions. If InstanceContextMode is PerCall, the resulting value is the number of concurrent calls. If a message arrives while the maximum number of InstanceContext objects already exist, the message is held until an InstanceContext object closes.

You can also set the values of this attribute by using the <serviceThrottling> element in an application configuration file.