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From Pavan K Narayanan <pavan.naraya...@gmail.com>
Subject Re: Mahout Collaborative Filtering using a parallel matrix factorization
Date Sat, 26 Oct 2013 16:18:26 GMT
not that i know of. only a mahout committer can answer this question.
On Oct 26, 2013 9:26 PM, "barnold4238@gmail.com" <barnold4238@gmail.com>
wrote:

> I will give that a try. Is there a hadoop memory setting that I would need
> to change to get it working in 0.8?
>
> Thanks!
> Brian
>
> > On Oct 26, 2013, at 10:09 AM, Pavan K Narayanan <
> pavan.narayanan@gmail.com> wrote:
> >
> > Usually NullPointerException occurs when you have blanks in one of the
> > rows. Try checking the data and run it again.
> >
> > If you still encounter the same error, chances are likely that there is a
> > bug. Try to use Mahout 0.5 for this job. this uses reduced-side join
> > whereas 0.6 and 0.7 uses map-side join which means even though you are
> > using hadoop, you are still leveraging on sequential processing and not
> > utilizing distributed processing completely.
> >
> > Regards,
> >
> >
> >> On 26 October 2013 20:23, Brian Arnold <barnold4238@gmail.com> wrote:
> >>
> >> Here you are!
> >>
> >> 210203836,1174297,-2.0
> >> 210237476,1174297,20.0
> >> 210813956,1174297,14.0
> >> 211661676,1174297,12.0
> >> 211998596,1174297,82.0
> >> 212749796,1174297,-2.0
> >> 213212036,1174297,20.0
> >> 213649036,1174297,76.0
> >> 213778836,1174297,20.0
> >> 213963836,1174297,48.0
> >> 214090956,1174297,20.0
> >> 214539916,1174297,14.0
> >> 214955876,1174297,20.0
> >>
> >> Thanks so much for your help!
> >>
> >>
> >> On Sat, Oct 26, 2013 at 1:38 AM, Pavan K Narayanan <
> >> pavan.narayanan@gmail.com> wrote:
> >>
> >>> can you kindly post sample of your input data. i am interested to see
> the
> >>> format of your csv file
> >>>> On Oct 26, 2013 1:59 AM, "Brian Arnold" <barnold4238@gmail.com>
> wrote:
> >>>>
> >>>> Hey Everyone,
> >>>>
> >>>> I was hoping that someone could help me out with the
> >>>> ParallelALSFactoirzationJob that I am trying to run.  I have been
> >> trying
> >>> to
> >>>> run this over a 27GB dataset of customer transaction data, and the job
> >>>> keeps failing with a null pointer exception. I am running with Mahout
> >> 0.8
> >>>> and the following parameters --lambda 0.05 --implicitFeedback true
> >>>> --numFeatures 20 --numIterations 1 --tempDir temp/mahout_als
> >>>> --numThreadsPerSolver 1.
> >>>> ParallelALSFactorizationJob-ItemRatingVectorsMapper-Reducer completes
> >>> fine,
> >>>> ParallelALSFactorizationJob-TransposeMapper-Reducer completes fine,
> >>>> ParallelALSFactorizationJob-AverageRatingMapper-Reducer completes
> fine,
> >>> but
> >>>> it fails on Recompute U, iteration (2/1), (1 threads, 5 features,
> >>> implicit
> >>>> feedback).
> >>>>
> >>>>
> >>>> Here is the stacktrace I am receiving:
> >>>>
> >>>> java.lang.RuntimeException: java.lang.NullPointerException
> >>>>        at
> >>
> org.apache.hadoop.mapreduce.lib.map.MultithreadedMapper.run(MultithreadedMapper.java:149)
> >>>>        at
> >>
> org.apache.mahout.cf.taste.hadoop.als.MultithreadedSharingMapper.run(MultithreadedSharingMapper.java:53)
> >>>>        at
> >>> org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:763)
> >>>>        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:363)
> >>>>        at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
> >>>>        at java.security.AccessController.doPrivileged(Native Method)
> >>>>        at javax.security.auth.Subject.doAs(Subject.java:396)
> >>>>        at
> >>
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1232)
> >>>>        at org.apache.hadoop.mapred.Child.main(Child.java:249)
> >>>> Caused by: java.lang.NullPointerException
> >>>>        at
> >>
> org.apache.mahout.math.als.ImplicitFeedbackAlternatingLeastSquaresSolver.getYtransponseCuMinusIYPlusLambdaI(ImplicitFeedbackAlternatingLeastSquaresSolver.java:95)
> >>>>        at
> >>
> org.apache.mahout.math.als.ImplicitFeedbackAlternatingLeastSquaresSolver.solve(ImplicitFeedbackAlternatingLeastSquaresSolver.java:51)
> >>>>        at
> >>
> org.apache.mahout.cf.taste.hadoop.als.SolveImplicitFeedbackMapper.map(SolveImplicitFeedbackMapper.java:54)
> >>>>        at
> >>
> org.apache.mahout.cf.taste.hadoop.als.SolveImplicitFeedbackMapper.map(SolveImplicitFeedbackMapper.java:29)
> >>>>        at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145)
> >>>>        at
> >>
> org.apache.hadoop.mapreduce.lib.map.MultithreadedMapper$MapRunner.run(MultithreadedMapper.java:268)
> >>>>
> >>>>
> >>>> Thanks so much!
> >>>>
> >>>> Brian
> >>
>

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