BottleNeck/delay when Calling WCF service

Question

I have created a simple WCF service with a method Do work, which sleeps for 15 seconds and then return a string. Its a Singleton service with multiple Concurrency.

The client(.net Desktop Application) has a for loop of 100 to call this function. I want to see how many threads i can process at one time and increase performance.

I am using NetTCP binding and have added the performance parameters

Server config

<services>
  <service name="WCFService.WCFService" behaviorConfiguration="mexbahaviour">
    <endpoint address="WCFService" binding="netTcpBinding" contract="WCFService.IWCFService" ></endpoint>
    <endpoint address="WCFService" binding="netNamedPipeBinding" contract="WCFService.IWCFService" ></endpoint>
    <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" ></endpoint>
    <host>
      <baseAddresses>
        <add baseAddress="http://localhost:8090/ "/>
        <add baseAddress="net.tcp://localhost:8091/ "/>
        <add baseAddress="net.pipe://localhost/ "/>
      </baseAddresses>
    </host>
  </service>
</services>
<behaviors>
  <serviceBehaviors>
    <behavior name="mexbahaviour">
      <serviceMetadata httpGetEnabled="true" />
      <serviceThrottling maxConcurrentCalls="300" maxConcurrentSessions="300"
        maxConcurrentInstances="600" />
    </behavior>
  </serviceBehaviors>
</behaviors>

The issue is the that the request is not hitting the server fast enough. Initial sec there are 4 request, but after that there are 2 requests per seconds. The output window on service looks like this.

So in this a new thread is created whenever a requests hit the service and logs the time it was received and the goes to sleep.

I did Add connection Management section on the client side

<connectionManagement>
  <add address="*" maxconnection="100"/>
</connectionManagement>

Is the delay due to thread creation? or some service-throttling limitation that i am hitting?

Please Give suggestions what i do.

I also tried to implement using this article which helped Boost WCF Performance

Answer 1

I think, this is based on a basic policy of thread pool. You can modify minThreads as follows,

int worker, int io;
ThreadPool.GetMinThreads(out worker, out io); 
ThreadPool.SetMinThreads(worker, 100 - io); // 100 is just sample value.