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https://issues.apache.org/jira/browse/SPARK-20328?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15968232#comment-15968232
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Michael Gummelt commented on SPARK-20328:
-----------------------------------------

cc [~colorant] [~hfeng] [~vanzin]

> HadoopRDDs create a MapReduce JobConf, but are not MapReduce jobs
> -----------------------------------------------------------------
>
>                 Key: SPARK-20328
>                 URL: https://issues.apache.org/jira/browse/SPARK-20328
>             Project: Spark
>          Issue Type: Bug
>          Components: Spark Core
>    Affects Versions: 2.1.0, 2.1.1, 2.1.2
>            Reporter: Michael Gummelt
>
> In order to obtain {{InputSplit}} information, {{HadoopRDD}} creates a 
> MapReduce {{JobConf}} out of the Hadoop {{Configuration}}: 
> https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala#L138
> Semantically, this is a problem because a HadoopRDD does not represent a 
> Hadoop MapReduce job.  Practically, this is a problem because this line: 
> https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala#L194
>  results in this MapReduce-specific security code being called: 
> https://github.com/apache/hadoop/blob/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/security/TokenCache.java#L130,
>  which assumes the MapReduce master is configured.  If it isn't, an exception 
> is thrown.
> So I'm seeing this exception thrown as I'm trying to add Kerberos support for 
> the Spark Mesos scheduler.  I have a workaround where I set a YARN-specific 
> configuration variable to trick {{TokenCache}} into thinking YARN is 
> configured, but this is obviously suboptimal.
> The proper fix to this would likely require significant {{hadoop}} 
> refactoring to make split information available without going through 
> {{JobConf}}, so I'm not yet sure what the best course of action is.



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