Binary file downloads are slow

Question

I have a file that I am attempting to return to a web client using HttpResponseMessage. The code works, but the transfer speed is five to ten times slower than simply fetching the same file from an IIS virtual directory. I have verified that it's not an encoding issue by monitoring my download bandwidth consumption, which never breaks 250 kilobytes per second, where the direct download from IIS is typically five times that.

Here's the code, stripped to its essentials and with error trapping removed for clarity:

// Succeeded in getting the stream opened, so return with HTTP 200 status to the client. var stream = new FileStream(uncPath, FileMode.Open,FileAccess.Read, FileShare.Read); HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK); result.Content = new StreamContent(stream); result.Content.Headers.ContentType = new MediaTypeHeaderValue(MimeExtensionHelper.GetMimeType(uncPath)); return result;

Am I missing something?

What does MimeExtensionHelper.GetMimeType(uncPath) return? Have you tried hardcoding a value result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");? — DaveB
– DaveB, Commented Dec 8, 2014 at 22:00
I would say that your anti-virus is scanning the binary file as it comes in. Disable it and report back. — Mathemats
– Mathemats, Commented Dec 9, 2014 at 4:17
Thanks. It's delivering the correct MIME type - in this case, image/jpeg for most of what it does. I have just found out by experimentation that if I read the entire file into a byte array and use a ByteArrayContent instead of StreamContent the file transfer goes from 13 seconds to under 3 (for a 2.5MB file, transferred from my hosted server to my desktop). So it has something to do with the read buffering of the stream. Giving the stream a large buffer size when opening the file does not help, strangely. It's as though the HttpResponse is reading and writing one byte at a time. — Andrew Forber
– Andrew Forber, Commented Dec 9, 2014 at 4:32
The slowness occurs regardless of antivirus, whether the file in question is on a local or network drive (relative to the web server), or buffer size allocated in the call to the FileStream constructor. It's odd that this should be, by default, so slow. — Andrew Forber
– Andrew Forber, Commented Dec 10, 2014 at 20:38
Did you ever figure this one out? I have posted a similar question here: stackoverflow.com/questions/32992081/… — TommyN
– TommyN, Commented Oct 13, 2015 at 11:40

Collectives™ on Stack Overflow

Binary file downloads are slow

0

Linked

Hot Network Questions

Collectives™ on Stack Overflow

0

Know someone who can answer? Share a link to this question via email, Twitter, or Facebook.

Linked