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https://issues.apache.org/jira/browse/HADOOP-7611?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14235906#comment-14235906
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Tsuyoshi OZAWA commented on HADOOP-7611:
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Let me check this.
> SequenceFile.Sorter creates local temp files on HDFS
> ----------------------------------------------------
>
> Key: HADOOP-7611
> URL: https://issues.apache.org/jira/browse/HADOOP-7611
> Project: Hadoop Common
> Issue Type: Bug
> Components: io
> Affects Versions: 0.20.2
> Environment: CentOS 5.6 64-bit, Oracle JDK 1.6.0_26 64-bit
> Reporter: Bryan Keller
>
> When using SequenceFile.Sorter to sort or merge sequence files that exist in
> HDFS, it attempts to create temp files in a directory structure specified by
> mapred.local.dir but on HDFS, not in the local file system. The problem code
> is in MergeQueue.merge(). Starting at line 2953:
> {code}
> Path outputFile = lDirAlloc.getLocalPathForWrite(
> tmpFilename.toString(),
> approxOutputSize, conf);
> LOG.debug("writing intermediate results to " + outputFile);
> Writer writer = cloneFileAttributes(
>
> fs.makeQualified(segmentsToMerge.get(0).segmentPathName),
> fs.makeQualified(outputFile),
> null);
> {code}
> The outputFile here is a local path without a scheme, e.g.
> "/mnt/mnt1/mapred/local", specified by the mapred.local.dir property. If we
> are sorting files on HDFS, the fs object is a DistributedFileSystem. The call
> to fs.makeQualified(outputFile) appends the fs object's scheme to the local
> temp path returned by lDirAlloc, e.g. hdfs://mnt/mnt1/mapred/local. This
> directory is then created (if the proper permissions are available) on HDFS.
> If the HDFS permissions are not available, the sort/merge fails even though
> the directories exist locally.
> The code should instead always use the local file system if retrieving a path
> from the mapred.local.dir property. The unit tests do not test this
> condition, they only test using the local file system for sort and merge.
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