[tahoe-lafs-trac-stream] [tahoe-lafs] #1670: KeyError in mutable retrieve

[tahoe-lafs]

#1670: KeyError in mutable retrieve
-------------------------+-------------------------------------------------
     Reporter:  vikarti  |      Owner:  davidsarah
         Type:  defect   |     Status:  new
     Priority:           |  Milestone:  soon
  critical               |    Version:  1.9.1
    Component:  code-    |   Keywords:  mutable retrieve error tahoe-backup
  mutable                |
   Resolution:           |
Launchpad Bug:           |
-------------------------+-------------------------------------------------

Comment (by kevan):

 It looks like the mutable filenode modification code in
 {{{MutableFileVersion}}} reacts to an {{{UncoordinatedWriteError}}} by
 performing a map update, then trying the operation again. That map update
 will update the {{{MutableFileVersion}}}'s internal servermap, but not its
 internal verinfo tuple. If the {{{UncoordinatedWriteError}}} is due to a
 concurrent update operation that updated all or most (enough for the
 version to be unrecoverable, anyway) of the shares associated with the
 {{{MutableFileVersion}}}'s version of the mutable file, then we would see
 the {{{KeyError}}} reported by vikarti and others. Someone (likely me, if
 no one gets around to it before next weekend) should look over the
 incident logs to see if they support or refute this theory.

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Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1670#comment:9>
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