[Cyberduck-trac] [Cyberduck] #185: Slow SFTP transfers

Cyberduck trac at trac.cyberduck.ch
Fri Nov 12 16:09:20 CET 2010

#185: Slow SFTP transfers
    Reporter:  wout.mertens@…          |        Owner:  dkocher      
        Type:  enhancement             |       Status:  closed       
    Priority:  high                    |    Milestone:  4.0          
   Component:  sftp                    |      Version:  3.5          
    Severity:  major                   |   Resolution:  fixed        
    Keywords:                          |     Platform:  Mac OS X 10.6
Architecture:  Intel                   |  

Comment (by dkocher):

 Replying to [comment:68 caeies]:
 > Replying to [comment:66 dkocher]:
 > > Replying to [comment:62 caeies]:
 > > > Ok reading you code, I think that the main problem is that you are
 waiting for the ACK before continuing to send data, while openSSH just
 send stuff as fast as it can until he fills the queue, then check for ACK
 when the sent queue is filled ...
 > >
 > > I don't see how the patch attached changes this behaviour. It will
 still toggle between writing and reading the status.
 > Yes, but after ''parallelism'' requests only. So it doesn't wait for the
 network latency just after sending the first request and so on ... it will
 read back the answer only after the 64th requests, so when the server
 starts to reply to the requests and that the requests are back to the
 > Anyway, the main problem of this patch is the lasts 64th requests that
 aren't checked at the end of the download.
 > Hope I'm clear
 > Caeies.

 I understand and the patch my own patch attached should fix this issue
 with the same characteristics of sending out multiple write requests
 before reading any status. Let me know about the results compared to no
 parallelism. Thanks again for your help here, much appreciated!

Ticket URL: <http://trac.cyberduck.ch/ticket/185#comment:69>
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