[tahoe-dev] [tahoe-lafs] #1170: new-downloader performs badly when downloading a lot of data from a file

[tahoe-lafs]

#1170: new-downloader performs badly when downloading a lot of data from a file
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     Reporter:  zooko         |       Owner:                                           
         Type:  defect        |      Status:  closed                                   
     Priority:  critical      |   Milestone:  1.8.0                                    
    Component:  code-network  |     Version:  1.8β                                     
   Resolution:  fixed         |    Keywords:  immutable download performance regression
Launchpad Bug:                |  
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Changes (by zooko):

  * status:  new => closed
  * resolution:  => fixed


Comment:

 Recap of this ticket: there were two major performance regressions in
 1.8.0c1 or c2 vs. 1.7.1. One was the superlinear computation in spans and
 the other was a server-selection algorithm that would in some cases choose
 to get multiple shares from one server unnecessarily. Both of those are
 fixed in 1.8.0c4 (upcoming) and benchmarks by various people indicate that
 1.8.0c4 immutable download is only a little slower (~10% slower) than
 1.7.1 in the worst case and much faster (e.g. ~400% faster) in other
 common cases.

 So, this ticket is done well enough for v1.8.0 final. I strongly suspect
 that the remaining ~10% slowdown has to do with more computation after
 receiving a block and before sending the next get_block request, which
 would probably be best addressed by implementing #1110 or #1187.

 Thanks very much to Brian, Terrell, David-Sarah, Kyle, and anyone else who
 helped slay this damned tenacious issue. :-) Hooray! It is dead! Good-bye
 ticket #1170!

 P.S. The gentle reader, before looking away from this ticket forever and
 ever, might want to look at the following comments and perhaps transcribe
 some of their important bits out to a fresh new ticket: comment:43,
 comment:90, comment:92. And by "the gentle reader", I ''guess'' I mean
 Brian.

-- 
Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1170#comment:113>
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