WCF slow first call - performance

Question

I create one WCF service from scratch with the Visual Studio project creation wizard.
Here is the interface of the service:
namespace ServiceTest {
[ServiceContract]
public interface IService1 {
[OperationContract]
string GetData(int value);
[OperationContract]
CompositeType GetDataUsingDataContract(CompositeType composite);
}
[DataContract]
public class CompositeType {
bool boolValue = true;
string stringValue = "Hello ";
[DataMember]
public bool BoolValue {
get { return boolValue; }
set { boolValue = value; }
}
[DataMember]
public string StringValue {
get { return stringValue; }
set { stringValue = value; }
}
}
And the implementation:
namespace ServiceTest {
public class Service1 : IService1 {
public string GetData(int value) {
return string.Format("You entered: {0}", value);
}
public CompositeType GetDataUsingDataContract(CompositeType composite) {
if (composite == null) {
throw new ArgumentNullException("composite");
}
if (composite.BoolValue) {
composite.StringValue += "Suffix";
}
return composite;
}
}
And Web.config:
<configuration>
<appSettings>
<add key="aspnet:UseTaskFriendlySynchronizationContext" value="true"/>
</appSettings>
<system.web>
<compilation debug="true" targetFramework="4.6.1"/>
<httpRuntime targetFramework="4.6.1"/>
<httpModules>
<add name="ApplicationInsightsWebTracking" type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web"/>
</httpModules>
</system.web>
<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior>
<serviceMetadata httpGetEnabled="true" httpsGetEnabled="true"/>
<serviceDebug includeExceptionDetailInFaults="false"/>
</behavior>
</serviceBehaviors>
</behaviors>
<protocolMapping>
<add binding="basicHttpsBinding" scheme="https"/>
</protocolMapping>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true"/>
</system.serviceModel>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true">
<remove name="ApplicationInsightsWebTracking"/>
<add name="ApplicationInsightsWebTracking" type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web"
preCondition="managedHandler"/>
</modules>
<directoryBrowse enabled="true"/>
<validation validateIntegratedModeConfiguration="false"/>
</system.webServer>
</configuration>
And in the other side, the client (a simple console application) with the code:
namespace ClientServiceTest {
class Program {
static void Main(string[] args) {
Service1Client client = new Service1Client();
DateTime begin = DateTime.Now;
string res = client.GetData(0);
TimeSpan interval = DateTime.Now - begin;
;
}
}
My question is:
On the first call, the interval.TotalMilliseconds is around 250.
If I play again the call with the same client, I get around 10 ms.
How can I reduce this initial cost?

Answer 1

I'm assuming the first call causes the Application Pool to load and then load the service and everything is already loaded for the second call.
In IIS Manager, try setting the Start Mode for the Application Pool that your WCF service is running in to AlwaysRunning and the Idle Time-out Action to Suspend. You might also want to increase the Idle Time-out(minutes).