Question

I need to test a Data Context and see what behavior it has under multiple simultaneous requests, for that I made a simple console application that [in theory] would send these requests:

private static DateTime startTime = DateTime.Now.AddSeconds(5);
public static Random rand = new Random();

static void Main(string[] args)
{
    const byte testThreads = 10;

    ThreadStart[] threadStarts = new ThreadStart[testThreads];
    Thread[] threads = new Thread[testThreads];

    for (byte i = 0; i < testThreads; i++)
    {
        threadStarts[i] = new ThreadStart(ExecutePOST);
        threads[i] = new Thread(threadStarts[i]);
    }

    for (byte i = 0; i < testThreads; i++){ threads[i].Start(); }

    for (byte i = 0; i < testThreads; i++){ threads[i].Join(); }
}

The called function is

private static void ExecutePOST()
{
    while (DateTime.Now < startTime) { }

    Console.WriteLine("{0} STARTING TEST", DateTime.Now.Millisecond);
    WebRequest webRequest = WebRequest.Create(/*URL*/);
    webRequest.ContentType = "application/x-www-form-urlencoded";
    webRequest.Method = "POST";

    string name = string.Format("Test {0}", Program.rand.Next(1000));

    byte[] bytes = Encoding.ASCII.GetBytes(/*PARAMETERS*/);
    Stream output = null;
    try
    {
        webRequest.ContentLength = bytes.Length;
        output = webRequest.GetRequestStream();
        output.Write(bytes, 0, bytes.Length);

        Console.WriteLine("{0}:{1}", DateTime.Now.Millisecond, name);
    }
    catch (WebException ex)
    {
        Console.WriteLine(ex.Message);
    }
    finally
    {
        if (output != null)
        {
            output.Close();
        }
    }
}

The output I get is:

Can anyone please explain this behavior? Why is it stopping after two requests?

Thank you

Answer 1

Yes, this is because the number of connections per URL is limited to 2 by default – the connections are pooled.

You’re hogging the connection by writing data to the request stream, but then never getting the response. A simple:

using (webRequest.GetResponse()) {}

at the end of the method is likely to sort it out. That will finish the request and release the connection to be used by another request.

Also note that a using statement for the output stream would make your code simpler too.