WCF more than 50 concurent long running request - wcf

Question

Hy, I have a WCF Test service, it does nothing only a thread.sleep(10000) and I call it from 200 clients.
The problem is the response time is greater and greater, after 10 minutes over 40 sec...
I have tired to change web.config and machine.config too.
We have Windows 2008 r2 and IIS 7.5
In my web.config
<serviceThrottling maxConcurrentCalls="100" maxConcurrentSessions="400" maxConcurrentInstances="2000" />
In my macine.config
<processModel autoConfig="false" logLevel="None" maxIoThreads="1000" maxWorkerThreads="1000" minIoThreads="100" minWorkerThreads="100" />
In my Aspnet.config
<applicationPool maxConcurrentRequestsPerCPU="5000" maxConcurrentThreadsPerCPU="0" requestQueueLimit="5000" />
The WCF Service:
public interface ISampleService
{
[OperationContractAttribute]
string SampleMethod(string msg);
}
public class SampleService : ISampleService
{
public string SampleMethod(string msg)
{
Thread.Sleep(10000);
return msg;
}
}

Answer 1

Here my solution:
[ServiceContract(Namespace = "http://microsoft.wcf.documentation")]
public interface ISampleService
{
[OperationContract]
Task<string> SampleMethod(string msg);
}
public class SampleService : ISampleService
{
async Task<string> ISampleService.SampleMethod(string msg)
{
var task = Task.Factory.StartNew((param) =>
{
return "Return from Server : " + msg;
}, TaskContinuationOptions.LongRunning);
await Task.Delay(10000);
return await task.ConfigureAwait(false);
}
}
And i need only the web.config changes:
<serviceThrottling maxConcurrentCalls="500" maxConcurrentSessions="1000" maxConcurrentInstances="2000" />