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https://issues.apache.org/jira/browse/SPARK-21549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16173184#comment-16173184
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Sergey Zhemzhitsky commented on SPARK-21549:
--------------------------------------------
[~mridulm80], [~WeiqingYang], [~ste...@apache.org],
I've implemented the fix in this PR
(https://github.com/apache/spark/pull/19294), which sets user's current working
directory (which is typically her home directory in case of distributed
filesystems) as output directory.
The patch allows using OutputFormats which write to external systems,
databases, etc. by means of RDD API.
I far as I understand the requirement for output paths to be specified is only
necessary to allow files to be committed to an absolute output location, that
is not the case for output formats which write data to external systems.
So using user's working directory for such situations seems to be ok.
> Spark fails to complete job correctly in case of OutputFormat which do not
> write into hdfs
> ------------------------------------------------------------------------------------------
>
> Key: SPARK-21549
> URL: https://issues.apache.org/jira/browse/SPARK-21549
> Project: Spark
> Issue Type: Bug
> Components: Spark Core
> Affects Versions: 2.2.0
> Environment: spark 2.2.0
> scala 2.11
> Reporter: Sergey Zhemzhitsky
>
> Spark fails to complete job correctly in case of custom OutputFormat
> implementations.
> There are OutputFormat implementations which do not need to use
> *mapreduce.output.fileoutputformat.outputdir* standard hadoop property.
> [But spark reads this property from the
> configuration|https://github.com/apache/spark/blob/v2.2.0/core/src/main/scala/org/apache/spark/internal/io/SparkHadoopMapReduceWriter.scala#L79]
> while setting up an OutputCommitter
> {code:javascript}
> val committer = FileCommitProtocol.instantiate(
> className = classOf[HadoopMapReduceCommitProtocol].getName,
> jobId = stageId.toString,
> outputPath = conf.value.get("mapreduce.output.fileoutputformat.outputdir"),
> isAppend = false).asInstanceOf[HadoopMapReduceCommitProtocol]
> committer.setupJob(jobContext)
> {code}
> ... and then uses this property later on while [commiting the
> job|https://github.com/apache/spark/blob/v2.2.0/core/src/main/scala/org/apache/spark/internal/io/HadoopMapReduceCommitProtocol.scala#L132],
> [aborting the
> job|https://github.com/apache/spark/blob/v2.2.0/core/src/main/scala/org/apache/spark/internal/io/HadoopMapReduceCommitProtocol.scala#L141],
> [creating task's temp
> path|https://github.com/apache/spark/blob/v2.2.0/core/src/main/scala/org/apache/spark/internal/io/HadoopMapReduceCommitProtocol.scala#L95]
> In that cases when the job completes then following exception is thrown
> {code}
> Can not create a Path from a null string
> java.lang.IllegalArgumentException: Can not create a Path from a null string
> at org.apache.hadoop.fs.Path.checkPathArg(Path.java:123)
> at org.apache.hadoop.fs.Path.<init>(Path.java:135)
> at org.apache.hadoop.fs.Path.<init>(Path.java:89)
> at
> org.apache.spark.internal.io.HadoopMapReduceCommitProtocol.absPathStagingDir(HadoopMapReduceCommitProtocol.scala:58)
> at
> org.apache.spark.internal.io.HadoopMapReduceCommitProtocol.abortJob(HadoopMapReduceCommitProtocol.scala:141)
> at
> org.apache.spark.internal.io.SparkHadoopMapReduceWriter$.write(SparkHadoopMapReduceWriter.scala:106)
> at
> org.apache.spark.rdd.PairRDDFunctions$$anonfun$saveAsNewAPIHadoopDataset$1.apply$mcV$sp(PairRDDFunctions.scala:1085)
> at
> org.apache.spark.rdd.PairRDDFunctions$$anonfun$saveAsNewAPIHadoopDataset$1.apply(PairRDDFunctions.scala:1085)
> at
> org.apache.spark.rdd.PairRDDFunctions$$anonfun$saveAsNewAPIHadoopDataset$1.apply(PairRDDFunctions.scala:1085)
> at
> org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:151)
> at
> org.apache.spark.rdd.RDDOperationScope$.withScope(RDDOperationScope.scala:112)
> at org.apache.spark.rdd.RDD.withScope(RDD.scala:362)
> at
> org.apache.spark.rdd.PairRDDFunctions.saveAsNewAPIHadoopDataset(PairRDDFunctions.scala:1084)
> ...
> {code}
> So it seems that all the jobs which use OutputFormats which don't write data
> into HDFS-compatible file systems are broken.
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