使用多个代理客户端时,如何修复WCF中的BasicHttpBinding?

[问题似乎有点长,但请耐心等待。它有样本来源来解释问题。]

请考虑以下基本上是wcf主机的代码:

[ServiceContract (Namespace = "http://www.mightycalc.com")]
interface ICalculator
{
    [OperationContract]
    int Add (int aNum1, int aNum2);
}

[ServiceBehavior (InstanceContextMode = InstanceContextMode.PerCall)]
class Calculator: ICalculator
{
    public int Add (int aNum1, int aNum2) {
        Thread.Sleep (2000); //Simulate a lengthy operation
        return aNum1 + aNum2;
    }
}

class Program
{
    static void Main (string[] args) {
        try {
            using (var serviceHost = new ServiceHost (typeof (Calculator))) {
                var httpBinding = new BasicHttpBinding (BasicHttpSecurityMode.None);
                serviceHost.AddServiceEndpoint (typeof (ICalculator), httpBinding, "http://172.16.9.191:2221/calc");

                serviceHost.Open ();
                Console.WriteLine ("Service is running. ENJOY!!!");
                Console.WriteLine ("Type 'stop' and hit enter to stop the service.");
                Console.ReadLine ();

                if (serviceHost.State == CommunicationState.Opened)
                    serviceHost.Close ();
            }
        }
        catch (Exception e) {
            Console.WriteLine (e);
            Console.ReadLine ();
        }
    }
}

此外,WCF客户端程序是:

class Program
{
    static int COUNT = 0;
    static Timer timer = null;

    static void Main (string[] args) {
        var threads = new Thread[10];

        for (int i = 0; i < threads.Length; i++) {
            threads[i] = new Thread (Calculate);
            threads[i].Start (null);
        }

        timer = new Timer (o => Console.WriteLine ("Count: {0}", COUNT), null, 1000, 1000);
        Console.ReadLine ();
        timer.Dispose ();
    }

    static void Calculate (object state)
    {
        var c = new CalculatorClient ("BasicHttpBinding_ICalculator");
        c.Open ();

        while (true) {
            try {
                var sum = c.Add (2, 3);
                Interlocked.Increment (ref COUNT);
            }
            catch (Exception ex) {
                Console.WriteLine ("Error on thread {0}: {1}", Thread.CurrentThread.Name, ex.GetType ());
                break;
            }
        }

        c.Close ();
    }
}

基本上,我创建了10个代理客户端,然后在不同的线程上重复调用add service方法。现在,如果我运行这两个应用程序并使用netstat观察打开的TCP连接,我会发现:

• 如果客户端和服务器都在同一台计算机上运行,则TCP连接数等于代理对象数。这意味着所有的请求都是并行的。这很好。
• 如果我在一台单独的计算机上运行服务器,我观察到无论我创建多少代理对象,最多打开2个TCP连接。只有两个请求并行运行。这严重影响了处理速度。
• 如果切换到net.tcp绑定,一切都会正常工作(即使每个代理对象在不同的计算机上运行,也会有一个单独的tcp连接)。

我很困惑,无法使BasicHttpBinding使用更多的TCP连接。我知道这是一个很长的问题,但是请帮忙!