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From "Adam Szita (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PIG-5277) Spark mode is writing nulls among tuples to the output
Date Sun, 13 Aug 2017 16:21:00 GMT

    [ https://issues.apache.org/jira/browse/PIG-5277?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16124976#comment-16124976
] 

Adam Szita commented on PIG-5277:
---------------------------------

Thanks all for taking a look. [PIG-3655.sparkNulls.2.patch|https://issues.apache.org/jira/secure/attachment/12878809/PIG-3655.sparkNulls.2.patch]
is now committed to trunk as a workaround so that we have a green build.

I'll keep this jira "in progress" to indicate that this is preferably not a final solution.

> Spark mode is writing nulls among tuples to the output 
> -------------------------------------------------------
>
>                 Key: PIG-5277
>                 URL: https://issues.apache.org/jira/browse/PIG-5277
>             Project: Pig
>          Issue Type: Bug
>          Components: spark
>            Reporter: Adam Szita
>            Assignee: Adam Szita
>
> After committing PIG-3655 a couple of Spark mode tests (e.g. org.apache.pig.test.TestEvalPipeline.testCogroupAfterDistinct)
started failing on:
> {code}
> java.lang.Error: java.io.IOException: Corrupt data file, expected tuple type byte, but
seen 27
> 	at org.apache.pig.backend.hadoop.executionengine.HJob$1.hasNext(HJob.java:122)
> 	at org.apache.pig.test.TestEvalPipeline.testCogroupAfterDistinct(TestEvalPipeline.java:1052)
> Caused by: java.io.IOException: Corrupt data file, expected tuple type byte, but seen
27
> 	at org.apache.pig.impl.io.InterRecordReader.readDataOrEOF(InterRecordReader.java:158)
> 	at org.apache.pig.impl.io.InterRecordReader.nextKeyValue(InterRecordReader.java:194)
> 	at org.apache.pig.impl.io.InterStorage.getNext(InterStorage.java:79)
> 	at org.apache.pig.impl.io.ReadToEndLoader.getNextHelper(ReadToEndLoader.java:238)
> 	at org.apache.pig.impl.io.ReadToEndLoader.getNext(ReadToEndLoader.java:218)
> 	at org.apache.pig.backend.hadoop.executionengine.HJob$1.hasNext(HJob.java:115)
> {code}
> This is because InterRecordReader became much stricter after PIG-3655. Before it just
simply skipped these bytes thinking that they are just garbage on the split beginning. Now
when we expect a [proper tuple with a tuple type byte|https://github.com/apache/pig/blob/trunk/src/org/apache/pig/impl/io/InterRecordReader.java#L153]
we see these nulls and throw an Exception.
> As I can see it this is happening because JoinGroupSparkConverter has to return something
even when it shouldn't.
> When the POPackage operator returns a [POStatus.STATUS_NULL|https://github.com/apache/pig/blob/trunk/src/org/apache/pig/backend/hadoop/executionengine/spark/converter/JoinGroupSparkConverter.java#L211],
the converter shouldn't return a thing, but it can't do better than returning a null. This
then gets written out by Spark..



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