bad performance for the code to send Http request

Hi guys,

I am new to Http in C#. Here is my code segment. My performance test result is 1st time it takes long time, almost 30 seconds, and from the 2nd time to the 10th time, it takes very little time (expected).

TestBlade is a machine which is located in local LAN. I have tried with IE, very quick response each time.

Code:

---

            Uri server = new Uri("http://TestBlade:8080/monitor");
            WebClient myWebClient = new WebClient();
            // open file to read
            byte[] returnRawBytes;
            int counter = 10;
            try
            {
                Console.WriteLine("Testing TestBlade performance... ");
                while (counter > 0)
                {
                    // post data
                    Console.WriteLine("Round " + counter + " Begin time: " + DateTime.Now);
                    returnRawBytes = myWebClient.UploadData(server.AbsoluteUri, System.Text.Encoding.ASCII.GetBytes("Hello server"));
                    Console.WriteLine(System.Text.Encoding.ASCII.GetString(returnRawBytes));
                    Console.WriteLine("Round " + counter + " Complete time: " + DateTime.Now);
                    Thread.Sleep (10000);
                    counter--;
                }
            }
            catch (Exception e) // get any other error
            {
                Console.WriteLine(e.ToString());
                throw;
            }

---

Any ideas why 1st time is so slow?

One more idea, I found most of time is consumed on method UploadData. Is there any tools I could use to diagnose what is the method doing please?

Quote:

---

Originally Posted by Checker1977

Hi guys,

I am new to Http in C#. Here is my code segment. My performance test result is 1st time it takes long time, almost 30 seconds, and from the 2nd time to the 10th time, it takes very little time (expected).

TestBlade is a machine which is located in local LAN. I have tried with IE, very quick response each time.

Code:

---

            Uri server = new Uri("http://TestBlade:8080/monitor");
            WebClient myWebClient = new WebClient();
            // open file to read
            byte[] returnRawBytes;
            int counter = 10;
            try
            {
                Console.WriteLine("Testing TestBlade performance... ");
                while (counter > 0)
                {
                    // post data
                    Console.WriteLine("Round " + counter + " Begin time: " + DateTime.Now);
                    returnRawBytes = myWebClient.UploadData(server.AbsoluteUri, System.Text.Encoding.ASCII.GetBytes("Hello server"));
                    Console.WriteLine(System.Text.Encoding.ASCII.GetString(returnRawBytes));
                    Console.WriteLine("Round " + counter + " Complete time: " + DateTime.Now);
                    Thread.Sleep (10000);
                    counter--;
                }
            }
            catch (Exception e) // get any other error
            {
                Console.WriteLine(e.ToString());
                throw;
            }

---

Any ideas why 1st time is so slow?

---

Perhaps a "network sniffer" would help here: it would show what packets go across the network, and you can then see if it's your application that isn't sending the packet for half a minute, or if it's the other end not replying, or such.

--
Mats

Good idea! I have used tcpdump before. BTW: I just want to make sure there is no profile tool provided by VS or any Windows built-in tools which could provide "better" analysis performance. If they can analyze based on CLR knowledge, the performance analysis will be better -- while TCPDump is only for general purpose analysis. Anyway, TCPDump is enough and fine. :-)

Quote:

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Originally Posted by matsp

Perhaps a "network sniffer" would help here: it would show what packets go across the network, and you can then see if it's your application that isn't sending the packet for half a minute, or if it's the other end not replying, or such.

--
Mats

---

I have never written code for CLR (well, I wrote a program two steps beyond Hello, World, but I don't think that counts).

I'd expect there are performance tools to analyze CLR code, but I also expect that this won't tell you what the problem is - at least, not unless you KNOW that the packet is sent late, rather than something else.

--
Mats

You could also step through the code with a debugger and see if any line in particular hangs. Thirty seconds is a magnitude where you don't need a profiler.

Thanks man, my code hangs at UploadData. You mean I stepped into this function to see assembly code?

Quote:

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Originally Posted by CornedBee

You could also step through the code with a debugger and see if any line in particular hangs. Thirty seconds is a magnitude where you don't need a profiler.

---

If you check the MSDN page, you'll see that "this method supports Network Tracing", and links on how to do that. This would be a good place to investigate.

Also, what your server is doing with the data you are sending is going to be important as well.

I didn't thoroughly read your code since these things are more an issue of forgetting to do something, rather than coding errors, so bear with me if I say anything that is clearly demonstrated in your code.

Are you correctly following the HTTP protocol? These things are usually, in my experience, caused when you try to upload something while the server is not actually told to listen for a response. If any of this sounds plausible, just say so and I will mess with the code. Its been a while since I have messed with C# so to be honest... I didn't read the code.