[tahoe-dev] [tahoe-lafs] #748: Exception: <class 'allmydata.mutable.common.UncoordinatedWriteError'> when trying to create directory on testgrid

[tahoe-lafs]

#748: Exception: <class 'allmydata.mutable.common.UncoordinatedWriteError'> when
trying to create directory on testgrid
--------------------------+-------------------------------------------------
 Reporter:  toby.murray   |           Owner:  nobody
     Type:  defect        |          Status:  new   
 Priority:  major         |       Milestone:  1.5.0 
Component:  code-mutable  |         Version:  1.4.1 
 Keywords:                |   Launchpad_bug:        
--------------------------+-------------------------------------------------

Comment(by zooko):

 Attached is the foolscap logtool incident report.  The critical excerpt of
 that report looks like this:

 {{{
 # 05:32:47.692 [22866716]: entering loop
 # 05:32:47.693 [22866717]: current goal: before update: , sh0 to
 [trjdor3o], sh1 to [xiktf6ok], sh2 to [jfdpabh3], sh3 to [z2unqjbp], sh4
 to [qvqv7jmm], sh5 to [fcmlx6em], sh6 to [6fyx5u4z], sh7 to [ivjakubr],
 sh8 to [wfninubk], sh9 to [lwkv6cji]
 # 05:32:47.693 [22866718]: we are planning to push new seqnum=#1
 # 05:32:47.693 [22866719]: 10 queries still outstanding
 # 05:32:47.697 [22866720]: 10 shares sent
 # 05:32:47.744 [22866724]: _got_write_answer from qvqv7jmm
 # 05:32:47.744 [22866725]: entering loop
 # 05:32:47.745 [22866726]: current goal: before update: , sh0 to
 [trjdor3o], sh1 to [xiktf6ok], sh2 to [jfdpabh3], sh3 to [z2unqjbp], sh4
 to [qvqv7jmm], sh5 to [fcmlx6em], sh6 to [6fyx5u4z], sh7 to [ivjakubr],
 sh8 to [wfninubk], sh9 to [lwkv6cji]
 # 05:32:47.745 [22866727]: we are planning to push new seqnum=#1
 # 05:32:47.745 [22866728]: 9 queries still outstanding
 # 05:32:47.746 [22866729]: _got_write_answer from 6fyx5u4z
 # 05:32:47.746 [22866730]: entering loop
 # 05:32:47.747 [22866731]: current goal: before update: , sh0 to
 [trjdor3o], sh1 to [xiktf6ok], sh2 to [jfdpabh3], sh3 to [z2unqjbp], sh4
 to [qvqv7jmm], sh5 to [fcmlx6em], sh6 to [6fyx5u4z], sh7 to [ivjakubr],
 sh8 to [wfninubk], sh9 to [lwkv6cji]
 # 05:32:47.747 [22866732]: we are planning to push new seqnum=#1
 # 05:32:47.747 [22866733]: 8 queries still outstanding
 # 05:32:47.748 [22866734]: _got_write_answer from trjdor3o
 # 05:32:47.748 [22866735]: entering loop
 # 05:32:47.749 [22866736]: current goal: before update: , sh0 to
 [trjdor3o], sh1 to [xiktf6ok], sh2 to [jfdpabh3], sh3 to [z2unqjbp], sh4
 to [qvqv7jmm], sh5 to [fcmlx6em], sh6 to [6fyx5u4z], sh7 to [ivjakubr],
 sh8 to [wfninubk], sh9 to [lwkv6cji]
 # 05:32:47.749 [22866737]: we are planning to push new seqnum=#1
 # 05:32:47.749 [22866738]: 7 queries still outstanding
 # 05:32:47.750 [22866739]: _got_write_answer from fcmlx6em
 # 05:32:47.751 [22866740]: entering loop
 # 05:32:47.751 [22866741]: current goal: before update: , sh0 to
 [trjdor3o], sh1 to [xiktf6ok], sh2 to [jfdpabh3], sh3 to [z2unqjbp], sh4
 to [qvqv7jmm], sh5 to [fcmlx6em], sh6 to [6fyx5u4z], sh7 to [ivjakubr],
 sh8 to [wfninubk], sh9 to [lwkv6cji]
 # 05:32:47.751 [22866742]: we are planning to push new seqnum=#1
 # 05:32:47.752 [22866743]: 6 queries still outstanding
 # 05:32:47.753 [22866744]: _got_write_answer from fcmlx6em

     * 05:32:47.753 [22866745]: WEIRD our testv failed, so the write did
 not happen [INCIDENT-TRIGGER]
     * 05:32:51.776 [22866746]: somebody modified the share on us: shnum=5:
 I thought they had #1:R=7ahx, but testv reported #1:R=7ahx
 }}}

 Hm, so far I don't understand how the client was surprised by this chain
 of events.

 But, now it is time to go to work so I'll wonder about it later.

-- 
Ticket URL: <http://allmydata.org/trac/tahoe/ticket/748#comment:8>
tahoe-lafs <http://allmydata.org>
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