RESTful WCF call is blocked until previous call is complete - wcf

Question

I've got a simple WCF RESTful service being hosted in IIS. I call the WCF using a browser. I call the service simultaneously using different tabs in the browser. Below is the code for the service
[ServiceContract]
public interface IWCFService
{
[OperationContract]
[WebGet(UriTemplate = "DoWork", ResponseFormat = WebMessageFormat.Json)]
string DoWork();
}
public class WCFService : IWCFService
{
public string DoWork()
{
string ret = "Enter time is " + System.DateTime.Now + " " + System.DateTime.Now.Millisecond;
System.Threading.Thread.Sleep(10000);
ret += ". Exiting time is " + System.DateTime.Now + " " + System.DateTime.Now.Millisecond;
return ret;
}
}
And below is the web.config file
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior name="WCFService.WCFServiceBehavior">
<serviceMetadata httpGetEnabled="true" />
<serviceDebug includeExceptionDetailInFaults="false" />
</behavior>
</serviceBehaviors>
<endpointBehaviors>
<behavior name="WCFService.WCFServiceBehavior">
<webHttp/>
</behavior>
</endpointBehaviors>
</behaviors>
<services>
<service behaviorConfiguration="WCFService.WCFServiceBehavior" name="WCFService.WCFService">
<endpoint address="" binding="webHttpBinding" contract="WCFService.IWCFService" behaviorConfiguration="WCFService.WCFServiceBehavior">
</endpoint>
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
</service>
</services>
</system.serviceModel>
</configuration>
Even though I enter the address in quick successions the end time of the first is the beginning time of the second eg output of one page is
Enter time is 12/05/2015 4:55:24 PM 568.
Exiting time is 12/05/2015 4:55:34 PM 569.
then the next page is
Enter time is 12/05/2015 4:55:34 PM 578.
Exiting time is 12/05/2015 4:55:44 PM 579.
What is could be causing this and how do can I fix it so all calls are processed as soon as they arrive?

Answer 1

I'm not sure but you can try to set ConcurrencyMode on multiple with the ServiceBehavior attribute on the implementing class
[ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple)]
public class WCFService : IWCFService