Paralle.invoke Web服务获取403禁止访问

Question

I have method called SColl. This method invokes a webservice.

When using parallel.invoke I am getting a 403 (Forbidden Access) error. Sometimes in 1 or 2, like d1, d3, d4 returned records, but d2 and d5 returned forbidden access.

Parallel.Invoke(
    () =>
    {
        List<myclass>  d1 = SColl(param, param, param, param);
    },
    () =>
    {
        List<myclass>  d2 = SColl(param, param, param, param);
    },
    () =>
    {
        List<myclass>  d3 = SColl(param, param, param, param);
    },
    () =>
    {
        List<myclass>  d4 = SColl(param, param, param, param);
    },
    () =>
    {
        List<myclass>   d5 = SColl(param, param, param, param);
    });

public List<myclass> SColl(param, param, param, param)
{
    // fill param to pass to web service call 

    // ab = webservice is invoked

    // for loop fill data from webservice to list

    // return list
}

But if I do sequential calls, all the lists returns data. What is wrong with the service or at my end? Or is something related to machine? I am debugging this code in P4 single core with WinXP.

List<myclass> d1 = SColl(param, param, param, param);
List<myclass> d2 = SColl(param, param, param, param);
List<myclass> d3 = SColl(param, param, param, param);
List<myclass> d4 = SColl(param, param, param, param);
List<myclass> d5 = SColl(param, param, param, param);

Answer 1

Try turning off keep-alives in IIS for your web service. This should help a bit. Remember , that IIS on Win XP has a limit of incoming connections, so you're basically launching DoS attack on yourself ;-)