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From Robert Muir <rcm...@gmail.com>
Subject Re: Parallel tests in ANT, experiment volunteers welcome :)
Date Fri, 30 Dec 2011 20:49:45 GMT
On Fri, Dec 30, 2011 at 3:45 PM, Dawid Weiss
<dawid.weiss@cs.put.poznan.pl> wrote:
> Thanks Robert. Yes, the variation in certain suites is pretty large --
> if you open the generated execution times cache you can see the
> timings for each test suite. I've seen differences going into tens of
> seconds depending on the seed (and the environment?). What are your
> timing for ant-based splits? Roughly the same?
>

I think i got to the bottom of this. Depending upon your seed, 95% of
the time a test gets "RamDirectory" but 5% of the time it gets a
file-system backed implementation.

Because of this, depending upon environment, test times swing wildly
because of fsync(). For example in the last nightly build we fsynced
over 7,000 times in tests.

This is really crazy and I want to prolong the life of my SSD: see my
latest comment with a fix on LUCENE-3667. With that patch my times are
no longer swinging wildly.

(easy way to see what i am talking about: just run tests with
-Dtests.directory=MMapDirectory or something like that)

-- 
lucidimagination.com

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