In my case I need to reset think time to Zero to get max iteration in specified run. I can do this manually but it requires a lot amount of time to do that. I need to go through each web test request and set think time as Zero, which is tedious - as I have so many web requests and web tests.

 Adding this plug-in it navigates to all web tests and provides think time as Zero/targeted value during load test execution. So that we no need to edit each web test and web test step individually.

Plugin Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace MyCustomClass
{
    public class ResetThinkTime : Microsoft.VisualStudio.TestTools.WebTesting.WebTestPlugin
    {
        public override void PreRequest(object sender, Microsoft.VisualStudio.TestTools.WebTesting.PreRequestEventArgs e)
        {
            base.PreRequest(sender, e);
            e.Request.Timeout = 0;

            if (e.Request.ThinkTime > 10)
            {
                e.Request.ThinkTime = 0;
            }
        }
    }
}

After compiling the source add plug in to each web test.

  Because of your Load Test Agent machines

 Error : Exception      SocketException  An operation was attempted on a non-blocking socket that already had an operation in progress     Stack

System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: An operation was attempted on a non-blocking socket that already had an operation in progress

   at System.Net.Sockets.Socket.BeginConnectEx(EndPoint remoteEP, Boolean flowContext, AsyncCallback callback, Object state)

   at System.Net.Sockets.Socket.UnsafeBeginConnect(EndPoint remoteEP, AsyncCallback callback, Object state)

   at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception)

Solution: Some times in corp networks load test agent/controller machines uses internet proxy setting in that case - Proxy server will reject connections to the targeted servers saying

  Because of DOS attack

Error : “No connection could be made because the target machine actively refused it <IP Address>”

 Solution1: If the connections are made directly (without proxy) and still if you encounter Socket Exception then that could be due to the fact that Webserver is rejecting the connections as it receiving connection requests from the same host. In that case try adding more agents to distribute the load and use as many as IP’s in Agent configuration settings to generate the targeted load.

Solution2: Sometimes due to settings in web.config you will not be able to generate the targeted load then adjust throttling settings based on the processors

 <behaviors>
            <serviceBehaviors>
                <behavior name="WIBSBehavior">
                    <serviceDebug includeExceptionDetailInFaults="false" />
          <serviceThrottling maxConcurrentCalls="32" maxConcurrentSessions="30"/>
                </behavior>
            </serviceBehaviors>
</behaviors>