Faulty BRP task erroneously validated?
9 Aug 2015 11:17:01 UTC
Topic 198184
(moderation:
One of my Android devices recently froze. After restart it sent in one result as completed, even though the progress bar before the freeze reported 20%. Correspondingly, the reported CPU time is about 20% of the average time for this machine. Surprisingly, the task was nevertheless successfully validated (against an opencl-intel_gpu result).
I was wondering whether there could be a bug at work.
The relevant task is
p2030.20141113.G190.52-01.83.C.b5s0g0.00000_3280_1
from workunit 225002289
Faulty BRP task erroneously validated?
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Looking at the stderr for task#513670130 belonging to WU#225002289 it seems the task did finish normally but was restarted once after the science app had call boinc_finish. When restarted the output file for the completed tasks was found so no need to reprocess.
The progress report shown i Boinc was probably not accurate due to the crash/freeze and that goes for the reported run time as well. But everything else points to the task being completed normally as the stderr looks ok and the task was validated.
I'd say everything is ok and nothing to worry about even though the crash/freeze did somehow effect the reported run time.
We have some rather
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We have some rather pedantic/paranoid safeguards in place to prevent validation of partially completed results.
First, the result file itself is only generated at the end of computation, intermediate results are stored in checkpoint files but those are different from the final result file so there is not even a theoretical possibility that BOINC could somehow upload something that is meaningful to the validator before the computation is actually finished.
Also, the result file itself contains a special 'end of file' marker in the last line to guard against truncation errors or files being sent before writing the file is finished.
And then of course there is the comparison to a second hosts's results (which might be affected by the same problem tho, so the measures described before are not entirely useless).
HB
Thanks for checking!
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Thanks for checking!