[Cyberduck-trac] [Cyberduck] #8179: Download speed incorrect when resuming

[Cyberduck]

#8179: Download speed incorrect when resuming
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    Reporter:  duffy cola  |      Owner:
        Type:  defect      |     Status:  new
    Priority:  normal      |  Milestone:
   Component:  core        |    Version:  4.5.1
    Severity:  normal      |   Keywords:  Download speed
Architecture:              |   Platform:
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 Hi,

 I have to continue downloads quite often and the download speed is not
 correct initially. I assume the algorithm keeps a list of the amount
 downloaded in the previous N timesteps. Each timestep gives a speed sample
 with the number of bytes downloaded divided by the time delta. The total
 speed is then averaged over all of these timesteps.

 I believe the error is that in the initial time step the existing file
 size is not subtracted. Therefore you have a very high outlier in the list
 of speed samples, which slowly converges to the actual speed when new
 samples arrive. The error is gone once the buffer is full and the initial
 outlier is removed.

 Solutions:

 Quick Workaround: Instead of computing the mean, compute the median, which
 is not sensitive to a single outlier.
 Bugfix: Subtract the filesize from the amount downloaded for the first
 timestep.

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Ticket URL: <https://trac.cyberduck.io/ticket/8179>
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