Copy in c# is very slow

Question

I am trying to copy a lot of files using a loop and CopyTo method. The copy is very slow. abot 10 mb per minute! (in contrast to right click in mouse and copy).

Is there any alternatives to use, which are faster?

Please read the FAQ for guidance on how to improve the phrasing of your question http://stackoverflow.com/faq — Pooli, Jun 23 '11 at 10:24
I think it is a valid question if asked properly. For example is there any fast alternate I can use rather than `CopyTo` method which is quite slow as compared to Window's `rightclick->copy->paste` in C#? — Haris Hasan, Jun 23 '11 at 10:25
To abstract question ,i dont think Microsoft will improve that just because it's you're problem — Rosmarine Popcorn, Jun 23 '11 at 11:25

score 2 · Answer 1 · edited May 23 '17 at 12:27

2

I think this will help:

File.Copy vs. Manual FileStream.Write For Copying File

It also explains why the copy function is slow.

edited May 23 '17 at 12:27

Community

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answered Jun 23 '11 at 10:28

Peter

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Grant Thomas · Answer 2 · 2011-06-23T10:43:22.270

Yes, use FileStream to buffer accordingly. As an example, something along the lines of this ought to give you an idea:

using (var inputStream = File.Open(path, FileMode.Read),
    outputStream = File.Open(path, FileMode.Create))
{
    var bufferRead = -1;
    var bufferLength = 4096;
    var buffer = new byte[bufferLength];

    while ((bufferRead = inputStream.Read(buffer, 0, bufferLength)) > 0)
    {
        outputStream.Write(buffer, 0, bufferRead);
    }
}

Adjust the bufferLength accordingly. You could potentially build things around this to enhance its overall speed, but tweaking slightly should still provide a significant enough improvement.

score 1 · Answer 3 · answered Jun 23 '11 at 10:50

1

The fastest (and most convenient) way to copy a file is probably File.Copy. Is there a reason you are not using it?

answered Jun 23 '11 at 10:50

Jon

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Copy in c# is very slow

3 Answers3