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Concurrent download from Google Drive using Safari fails

Can someone shed some light on the issue below...


I attempted to download 2 large (~3GB) video files concurrently from Goggle Drive via it's web interface using the Safari browser (Version 14.1.2 bundled with Big Sur 11.5.2).


I stepped away from the computer while the downloads were in progress. When I returned, the downloads had seemed to complete successfully. However, one file would not play at all with QuickTime Player. The other file played at first, but the video froze about 2/3 of the way through the file. Re-running the downloads one file at a time avoided these problems.


An advisor at Apple Support concluded that the concurrent transfers had not run to completion (by comparing file sizes of the concurrent and single transfers). This was not obvious at first because although QuickTime indicated the full duration on its status bar, the encoded data frames from the last part of the video were missing in the (concurrently downloaded) file.


I'm left wondering whether it's good practice to simultaneously download multiple (large) files using the Safari browser.


Any thoughts or suggestions?


- Pie Lover

Mac mini 2018 or later

Posted on Sep 4, 2021 6:18 PM

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Posted on Sep 4, 2021 10:02 PM

I have seen this with a larger number (~ 10 or more) of large concurrent downloads, multi-GB each. But not with just ~ 2. I think it can be a function of the server where things are being downloaded from, and also your internet connection, which includes your router, home network as well as your internet provider. The constant multi-tasking and swapping between concurrent activities may make the downloads more prone to bit errors, which should be detected and corrected, but none of us have complete insight into all these variables. Another thing I have noticed: downloading large files one at a time is significantly faster than doing them concurrently, at least some of the time. There is clearly more overhead and work involved in balancing the load of multiple such jobs. Possibly thus more prone to errors.


I think you should learn from your empirical experiment and do large downloads one at a time in the future.

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Sep 4, 2021 10:02 PM in response to BlueberryLover

I have seen this with a larger number (~ 10 or more) of large concurrent downloads, multi-GB each. But not with just ~ 2. I think it can be a function of the server where things are being downloaded from, and also your internet connection, which includes your router, home network as well as your internet provider. The constant multi-tasking and swapping between concurrent activities may make the downloads more prone to bit errors, which should be detected and corrected, but none of us have complete insight into all these variables. Another thing I have noticed: downloading large files one at a time is significantly faster than doing them concurrently, at least some of the time. There is clearly more overhead and work involved in balancing the load of multiple such jobs. Possibly thus more prone to errors.


I think you should learn from your empirical experiment and do large downloads one at a time in the future.

Sep 5, 2021 4:49 AM in response to steve626

Thanks for sharing your experience and insight.


The Apple advisor also mentioned the communication link as a possible source of the problem. I was skeptical that this was the issue since I have an 50 Mbps FTTH (fibre to the home) connection to my ISP and the Mac mini is connected to the router using a 6 foot GigE ethernet cable. This configuration has extremely low packet loss.


That said, I think that I'll stick to sequential single file downloads in the future.


I wonder why there was no error indication from either Safari or macOS when the download stopped prematurely.


- Pie Lover

Concurrent download from Google Drive using Safari fails

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