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From Hanifi Gunes <hgu...@maprtech.com>
Subject Re: Regarding unit test failures -- patterns & possible fixes
Date Tue, 07 Apr 2015 00:55:49 GMT
I have just seen Jacques' comment under the patch. I am not sure whether we
should set forks to a fraction of available cores. Any ideas?


On Mon, Apr 6, 2015 at 5:52 PM, Hanifi Gunes <hgunes@maprtech.com> wrote:

> @Ted, I actually have a patch pending review for this at
> https://issues.apache.org/jira/browse/DRILL-2039. However, @Hakeem you
> may still end up in a troubling situation as your mac might have 4 logical
> cores =)
>
> *sysctl hw | grep **cpu* should tell you.
>
>
> -Hanifi
>
>
> On Mon, Apr 6, 2015 at 5:22 PM, Ted Dunning <ted.dunning@gmail.com> wrote:
>
>> Maven allows the forkCount to be set in terms of the number of cores on
>> the
>> machine by appending a C to the number.
>>
>> (I think)
>>
>>
>>
>> On Mon, Apr 6, 2015 at 5:15 PM, Abdel Hakim Deneche <
>> adeneche@maprtech.com>
>> wrote:
>>
>> > From my personal experience, using a forkCount of 4 makes some tests to
>> > timeout, not because there are some concurrent problems but just
>> because my
>> > machine is not powerful enough to run as many tests in parallel.
>> >
>> > On Mon, Apr 6, 2015 at 5:06 PM, Hanifi Gunes <hgunes@maprtech.com>
>> wrote:
>> >
>> > > Hey devs,
>> > >
>> > >
>> > > I have been dealing with sporadic unit test failures since last week.
>> I'd
>> > > like to share my findings on failing unit tests outlining the patterns
>> > > causing these.
>> > >
>> > > The general advice I was given was to run tests lowering the fork
>> count
>> > > (the default is 4). This sounds ok to get around the problem. If this
>> is
>> > > your intent feel free to give a try. However, I wanted to investigate
>> > this
>> > > further, went ahead and set fork count to 8, number of cores testing
>> > > machine has.
>> > >
>> > > The first set of failures manifested around TestUnionAll &
>> > > TestExampleQueries. After Hakeem's pointer, I noticed that some test
>> > cases
>> > > in TestUnionAll & TestExampleQueries creates & drops views with
the
>> same
>> > > name. In a concurrent settings(given fork count > 0) with no strict
>> > > ordering among test cases, this sure creates a havoc throwing
>> arbitrary
>> > > errors at each test run.
>> > https://issues.apache.org/jira/browse/DRILL-2684
>> > > takes care of this. After applying this fix, now I can cleanly run
>> > > java-exec tests, faster & consistently.
>> > >
>> > > Then my hive tests started failing since multiple test classes use the
>> > same
>> > > metadata folders and clean up after without caring whether other hive
>> > tests
>> > > are still running. I got a patch to unique-ify metadata folders for
>> test
>> > > class. https://issues.apache.org/jira/browse/DRILL-2685 tracks this
>> > > however
>> > > the patch is not public yet.
>> > >
>> > > The last problem relates to hive related tests living under jdbc
>> module.
>> > I
>> > > know that there has been an ongoing effort to migrate these tests from
>> > jdbc
>> > > module to where they belong. I am not sure about the timeframe for the
>> > > migration but I would think the sooner is better.
>> > >
>> > > To avoid further failures, I would strongly recommend devs to use view
>> > > names and external resources that are unique across test cases. One
>> idea
>> > is
>> > > to suffix view a view name with test case/class name for instance
>> prefer
>> > > using names_view_test_union_all rather than a more generic names_view.
>> > Also
>> > > with increasing number of test cases checked in, it takes more and
>> more
>> > > time to complete a test run. We should consider concurrent test runs
>> as a
>> > > legitimate everyday use case and design tests accordingly.
>> > >
>> > >
>> > > I would be interested in hearing other unit test failure patterns so
>> as
>> > to
>> > > be alert. Feel free to share if you discovered any.
>> > >
>> > >
>> > > Regards.
>> > > -Hanifi
>> > >
>> >
>> >
>> >
>> > --
>> >
>> > Abdelhakim Deneche
>> >
>> > Software Engineer
>> >
>> >   <http://www.mapr.com/>
>> >
>> >
>> > Now Available - Free Hadoop On-Demand Training
>> > <
>> >
>> http://www.mapr.com/training?utm_source=Email&utm_medium=Signature&utm_campaign=Free%20available
>> > >
>> >
>>
>
>

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