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From "Josh Wills (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CRUNCH-166) NullPointerException when attempting to use Sort.sortPairs
Date Thu, 21 Feb 2013 23:44:13 GMT

    [ https://issues.apache.org/jira/browse/CRUNCH-166?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13583674#comment-13583674
] 

Josh Wills commented on CRUNCH-166:
-----------------------------------

That's a puzzle. Are you doing any other manipulations to the Configuration object? Is it
possible that the pipeline that you're calling in writeTextFile isn't the same one that the
PCollection is originally created from? (I'm admittedly grasping at straws at this point.)
                
> NullPointerException when attempting to use Sort.sortPairs
> ----------------------------------------------------------
>
>                 Key: CRUNCH-166
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-166
>             Project: Crunch
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 0.5.0
>         Environment: Hadoop 1.0.4
>            Reporter: Matthew Hayes
>            Assignee: Josh Wills
>         Attachments: WordSortIT.java
>
>
> I'm attempting to count some strings and then order by the count descending.  My code
effectively looks like this:
> {code}
> PCollection<SomeType> records = pipeline.read(...);
> PCollection<String> stringsToCount = records.parallelDo(
>             new DoFn<SomeType, String>() {
>                 @Override
>                 public void process(SomeType input,Emitter<String> emitter) {
>                   if (input.getRecords() != null && input.getRecords().size()
> 0)
>                   {
>                     for (MyRecord record : input.getRecords())
>                     {
>                       emitter.emit(record.getValue().toString());
>                     }
>                   }                      
>                 }
>             },              
>             Writables.strings()
>         );
> PTable<String, Long> stats = Aggregate.count(stringsToCount);
> PCollection<Pair<String, Long>> sortedStats = Sort.sortPairs(stats, new ColumnOrder(2,
Order.DESCENDING));
> pipeline.writeTextFile(sortedStats,"somewhere");
> {code}
> The error I get is:
> {code}
> java.lang.NullPointerException
> 	at org.apache.crunch.lib.Sort$TupleWritableComparator.setConf(Sort.java:459)
> 	at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:62)
> 	at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:117)
> 	at org.apache.hadoop.mapred.JobConf.getOutputKeyComparator(JobConf.java:773)
> 	at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.<init>(MapTask.java:959)
> 	at org.apache.hadoop.mapred.MapTask$NewOutputCollector.<init>(MapTask.java:674)
> 	at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:756)
> 	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
> 	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:1121)
> 	at org.apache.hadoop.mapred.Child.main(Child.java:249)
> {code}
> Note that the line numbers are shifted because I added some debugging and recompiled.
 The NullPointerException is thrown in TupleWritableComparator.setConf() here:
> {code}
> String[] columnOrderNames = ordering.split(",");
> {code}
> I suppose "crunch.ordering" is not set, and therefore ordering is null.  When I check
the conf in job tracker I also don't see this property set.
> Am I doing something wrong?

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