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<div class="moz-cite-prefix">On 12/14/2015 03:44 AM, Andrus, Brian
Contractor wrote:<br>
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<p class="MsoNormal">All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have a small gluster filesystem on 3
nodes.<o:p></o:p></p>
<p class="MsoNormal">I have a perl program that multi-threads
and each thread writes it’s output to one of 3 files depending
on some results.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">My trouble is that I am seeing missing
lines from the output.<o:p></o:p></p>
<p class="MsoNormal">The input is a file of 500 lines. Depending
on the line, it would be written to one of three files, but
when I total the lines put out, I am missing anywhere from 4
to 8 lines.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">This is even the case if I use an input
file that should all go to a single file.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">BUT… when I have it write to /tmp or
/dev/shm, all of the lines expected are there.<o:p></o:p></p>
<p class="MsoNormal">This leads me to think there is something
not happy with gluster and concurrent writes.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here is the code for the actual write:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> flock(GOOD_FILES, LOCK_EX) or die $!;<o:p></o:p></p>
<p class="MsoNormal"> seek(GOOD_FILES, 0, SEEK_END) or die
$!;<o:p></o:p></p>
<p class="MsoNormal"> print GOOD_FILES
$lines_to_process[$tid-1] ."\n";<o:p></o:p></p>
<p class="MsoNormal"> flock(GOOD_FILES, LOCK_UN) or die $!;<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">So I would expect the proper file locking
is taking place.<o:p></o:p></p>
<p class="MsoNormal">Is it possible that gluster is not writing
because of a race condition?</p>
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May be because of caching? Could you try with "gluster volume set
<volname> performance.write-behind off"<br>
<br>
Pranith<br>
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<p class="MsoNormal"><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Any insight as to where to look for a
solution is appreciated.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Brian Andrus<o:p></o:p></p>
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