From: Paul Lynch <plynchnlm@...>
Date: 2009-01-18T01:10:55+09:00
Subject: Re: FileUtils.cp_r is slow?

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I did some more testing on this.  I found that if I ran FileUtils.cp_r or
FileUtils.cp from within irb, the speed was reasonable (maybe 30s to copy
25MB to my flash drive.)  But, if I double-clicked my script to run it, it
took about 30 minutes (roughly-- I didn't wait that long.)  I wrote my own
copy method that opens the files in binary mode and uses a 10 MB buffer size
(with the read and write methods) and speed dropped back down to 26s.  This
is still 6x slower than Windows drag and drop, but it is tolerable.

Here's my copy code, in case anyone else has this problem:
  def self.copy_file(from_file, to_file)
    buffer_size = 10*MB
    begin
      to_s = File.open(to_file, 'wb')
      File.open(from_file, 'rb') do |from_s|
        while(data = from_s.read(buffer_size))
          log("read #{data.length}")
          to_s.write(data)
        end
      end
    rescue
      log("Caught error: "+$!)
      to_s.close if to_s
      raise
    end
  end

On Wed, Jan 14, 2009 at 12:45 PM, Paul Lynch <plynchnlm@gmail.com> wrote:

> I wrote a ruby script to backup files from my hard drive to my flash
> drive.   For some reason, with one of my flash drives, copying files
> with FileUtils.cp_r is about 250 times slower than if I drag and drop
> the files from one drive to the other in Windows.  I'm suspecting a
> buffer size problem.  Is there a way to control the buffer size cp_r
> selects?  If not, what alternatives are there to FileUtils.cp_r?  (I
> am about to try writing my own, but someone must already have a
> solution....)
>
> --
> Paul Lynch
>
>


-- 
Paul Lynch

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