[tahoe-lafs-trac-stream] [tahoe-lafs] #1500: test_mutable.Update takes too long to run

[tahoe-lafs]

#1500: test_mutable.Update takes too long to run
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     Reporter:  warner        |      Owner:
         Type:  defect        |     Status:  new
     Priority:  major         |  Milestone:  1.9.0
    Component:  code-mutable  |    Version:  1.8.2
   Resolution:                |   Keywords:
Launchpad Bug:                |
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Comment (by kevan):

 Two of the four mutable files are created with 255 shares; this was meant
 to test the boundary calculations for MDMF caps (though the SDMF file
 isn't necessary for that). If I comment out lines 3290 and 3291 of
 test_mutable.py, the runtime on my machine drops from 121 seconds to 21
 seconds, suggesting that MDMF or SDMF files take a lot longer to process
 when created with a large number of shares. I'm not sure if that's a
 regression relative to 1.8.2; I'm not aware of any existing tests that
 exercise the code on files with a large number of shares.

 Using 255 shares isn't a reliable testing technique unless full-sized keys
 are also used, and full-sized keys won't be used by default in these tests
 (which is why they passed when the boundary calculations were wrong). I
 like the idea of testing files with 255 shares, but I don't think it is
 worthwhile to add minutes of runtime to the test suite for unreliable
 tests. Maybe we should add tests for this case in an area of the test
 suite that runs with larger keys and remove them from
 {{{test_mutable.Update}}}.

-- 
Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1500#comment:1>
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