WebClient.DownloadData hangs

Question

Hi.

I am trying to download file using WebClient.DownloadData. Usually the download is Ok, but for some Urls the download just hangs.

I've tried to override the WebClient, and set a timeout to the WebRequest, and it didn't help.

I've also tried to create WebRequest (with time out), then get the WebResponse, and then get the stream. When I've read the stream, It hangs again.

This is an example for a url that hangs: http://www.daikodo.com/genki-back/back-img/10genki-2.jpg.

Any Idea?

Answer 1

Here's what I use to download files from multiple servers. Note that I have set a limit to how much I want to read from the response stream because in the event I get a file exceeding the specified size, I don't want to read all of it. In my application, no URL's should result in a file exceeding the size; you may omit this limitation or increase this amount as needed.

int MaxBytes = 8912; // set as needed for the max size file you expect to download
string uri = "http://your.url.here/";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.Timeout = 5000; // milliseconds, adjust as needed
request.ReadWriteTimeout = 10000; // milliseconds, adjust as needed
using (var response = request.GetResponse())
{
    using (var responseStream = response.GetResponseStream())
    {
        // Process the stream
        byte[] buf = new byte[1024];
        string tempString = null;
        StringBuilder sb = new StringBuilder();
        int count = 0;
        do
        {
            count = responseStream.Read(buf, 0, buf.Length);
            if (count != 0)
            {
                tempString = Encoding.ASCII.GetString(buf, 0, count);
                sb.Append(tempString);
            }
        }
        while (count > 0 && sb.Length < MaxBytes);

        responseStream.Close();
        response.Close();

        return sb.ToString();
    }
}

I don't know if this will solve the hanging problem you are having, but it works well for my app.

Answer 2

I think it maybe your own problem since my app does not hang. Here is my code sample. Could you post your code here?

System.Net.WebClient client = new System.Net.WebClient();
string url = @"http://www.daikodo.com/genki-back/back-img/10genki-2.jpg";
string savePath = @"C:\Temp\test.jpg";

Console.WriteLine("Downloading from: " + url);
byte[] result = client.DownloadData(url);
System.IO.File.WriteAllBytes(savePath, result);

Console.WriteLine("Download is done! It has been saved to: " + savePath);
Console.ReadKey();

Answer 3

Have you tried monitoring the slow downloads using either Fiddler or Wireshark to see what's happening? e.g. is it just consistently slow all the way through or is it quite fast then just stops for some reason.

Alternatively maybe enabling network tracing may shed some light? http://msdn.microsoft.com/en-us/library/hyb3xww8.aspx