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From Brian Arnold <barnold4...@gmail.com>
Subject Re: Mahout Collaborative Filtering using a parallel matrix factorization
Date Thu, 31 Oct 2013 02:38:25 GMT
No, I have done a bunch of greping on the file and I still can't find
anything wrong with the data.  I was also going to try and run the
algorithm on Mahout 0.5 as suggested, but it seems that it is missing the
implicit feedback parameters.  Can I connect a debugger to a running mahout
job task somehow to figure out what is exactly going wrong?  Are there any
other suggestions on how next to proceed with debugging this issue?

Thanks!
Brian


On Sun, Oct 27, 2013 at 4:58 PM, Andrew Musselman <
andrew.musselman@gmail.com> wrote:

> No empty fields or extra empty lines, no extra whitespace?
>
> > On Oct 27, 2013, at 2:39 PM, "barnold4238@gmail.com" <
> barnold4238@gmail.com> wrote:
> >
> > Yea I have, and the job actually succeeded. But, in looking through my
> data, I still can't find anything that would look like it would cause the
> issue. Is there anything with the map side joins, and the size of my data
> that would potentially cause the issue? Is there a hadoop setting I would
> need to insure is set to a particular level so the job can succeed?
> >
> > Thanks!
> > Brian
> >> On Oct 27, 2013, at 3:53 PM, Sebastian Schelter <
> ssc.open@googlemail.com> wrote:
> >>
> >> Hi Brian,
> >>
> >> That error looks strange, could you try to run it on a toy dataset and
> >> see if you get the same error?
> >>
> >> --sebastian
> >>
> >>> On 25.10.2013 22:29, Brian Arnold 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
> >
> >
> >> On Oct 27, 2013, at 3:53 PM, Sebastian Schelter <
> ssc.open@googlemail.com> wrote:
> >>
> >> Hi Brian,
> >>
> >> That error looks strange, could you try to run it on a toy dataset and
> >> see if you get the same error?
> >>
> >> --sebastian
> >>
> >>> On 25.10.2013 22:29, Brian Arnold 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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