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From "Micah Whitacre (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CRUNCH-601) Short PCollections in SparkPipeline get length null.
Date Wed, 17 Aug 2016 14:20:20 GMT

    [ https://issues.apache.org/jira/browse/CRUNCH-601?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15424597#comment-15424597
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Micah Whitacre commented on CRUNCH-601:
---------------------------------------

So that code is very similar to what is already there in the Aggregate.length(..) method.
 The difficulty is that because the size is 0, it never chooses to materialize and therefore
never goes through that processing code.  

> Short PCollections in SparkPipeline get length null.
> ----------------------------------------------------
>
>                 Key: CRUNCH-601
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-601
>             Project: Crunch
>          Issue Type: Bug
>          Components: Spark
>    Affects Versions: 0.13.0
>         Environment: Running in local mode on Mac as well as in a ubuntu 14.04 docker
container
>            Reporter: Mikael Goldmann
>            Priority: Minor
>         Attachments: CRUNCH-601.patch, SmallCollectionLengthTest.java
>
>
> I'll attach a file with a test that I would expect to pass but which fails.
> It creates five PCollection<String> of lengths 0, 1, 2, 3, 4 gets the lengths,
runs the pipeline and prints the lengths. Finally it asserts that all lengths are non-null.
> I would expect it to print lengths 0, 1, 2, 3, 4 and pass.
> What it does is print lengths null, null, null, 3, 4 and fail.
> I think the underlying reason is the use of getSize() on an unmaterialized object and
assuming that when the estimate that getSize() returns is 0, then the PCollection is guaranteed
to be empty, which is false in some cases.



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