Why the buffer size changes my stream output?

I'm trying to stream a pdf file. Most of the files open without any problems but sometimes it fails. When it fails, it also looks like file size is smaller than the original one. For example, I was trying to open a 47K file but when the streamed output to the browser it's only 44.5K. When check the size of the stream (result.FileStream), it's 47K like it supposed to be.

I'm using Stream.Read to output the file to the browser. When I had a 开发者_如何学JAVAproblem, I was using buffer size of 10000 bytes. However, when I changed the buffer size from 10000 to 1000 the problem disappear and I was able to the file. I cannot explain why the change in the buffer size makes the streaming behave differently.

Here's the code I'm using result.FileStream is of type Stream:

using (result.FileStream)
{
    int length;
    const int byteSize = 1000;
    var buffer = new byte[byteSize];

    while ((length = result.FileStream.Read(buffer, 0, byteSize)) > 0 && Response.IsClientConnected)
    {
        Response.OutputStream.Write(buffer, 0, length);
        Response.Flush();
    }
}

Response.Close();

Please enlighten me because I definitely don't understand something.

You're using Response.Close(), which seems to be much more evil then the documentation would make you believe.

http://forums.iis.net/t/1152058.aspx