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https://issues.apache.org/jira/browse/MAHOUT-386?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12861410#action_12861410
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Sebastian Schelter commented on MAHOUT-386:
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tested it again, works fine now :)
> org.apache.mahout.cf.taste.hadoop.pseudo.RecommenderJob breaks when no
> usersFile is supplied
> --------------------------------------------------------------------------------------------
>
> Key: MAHOUT-386
> URL: https://issues.apache.org/jira/browse/MAHOUT-386
> Project: Mahout
> Issue Type: Bug
> Components: Collaborative Filtering
> Reporter: Sebastian Schelter
> Assignee: Sean Owen
> Fix For: 0.4
>
>
> When one tries to run org.apache.mahout.cf.taste.hadoop.pseudo.RecommenderJob
> without a usersFile (the file containing the userIDs to generate
> recommendations for) it throws an Exception in the Reducer.
> I took a look at the code and it seems that there are some needless things
> done:
> org.apache.mahout.cf.taste.hadoop.pseudo.RecommenderReducer tries to create a
> set of userIDs to generate recommendations for and fails to do this if no
> usersFile is supplied, when it tries to parse the preferences file. As far as
> I understand the code the Mapper already maps out only the userIDs to
> generate recommendations for, so there the check in the reducer is not even
> necessary, right? Correct me if I'm wrong.
> ---------------------------------------------------------------------------
> How to reproduce the error:
> 1) Create a file containing some sample preferences and call it
> mahout-testing.txt, mine looks like this
> 1,2,1
> 1,3,2
> 2,1,1
> 2,3,1
> 2) Run the Job without a usersFile, e.g.:
> hadoop jar core/target/mahout-core-0.4-SNAPSHOT.job
> org.apache.mahout.cf.taste.hadoop.pseudo.RecommenderJob
> -Dmapred.input.dir=./mahout-testing.txt -Dmapred.output.dir=/tmp/mahout/out
> --tempDir /tmp/mahout/tmp --recommenderClassName
> org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender
> java.lang.RuntimeException: Error in configuring object
> at
> org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:93)
> at
> org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:64)
> at
> org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:117)
> at
> org.apache.hadoop.mapred.ReduceTask.runOldReducer(ReduceTask.java:426)
> at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:411)
> at
> org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:215)
> Caused by: java.lang.reflect.InvocationTargetException
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at
> org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:88)
> ... 5 more
> Caused by: java.lang.NumberFormatException: For input string: "1,2,1"
> at
> java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
> at java.lang.Long.parseLong(Long.java:419)
> at java.lang.Long.parseLong(Long.java:468)
> at
> org.apache.mahout.cf.taste.hadoop.pseudo.RecommenderReducer.configure(RecommenderReducer.java:88)
> ... 10 more
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