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https://issues.apache.org/jira/browse/HADOOP-8437?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14908372#comment-14908372
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zhihai xu commented on HADOOP-8437:
-----------------------------------
thanks [~brahmareddy] for the patch! If the size of {{dirs}} is zero, it will
cause the following exception.
{code}
java.lang.IllegalArgumentException: n must be positive
at java.util.Random.nextInt(Random.java:250)
at
org.apache.hadoop.fs.LocalDirAllocator$AllocatorPerContext.confChanged(LocalDirAllocator.java:243)
{code}
same exception found at HADOOP-6766 and MAPREDUCE-635.
Can we avoid IllegalArgumentException by checking {{dirs.size()}} non-zero
before calling {{dirIndexRandomizer.nextInt}} with the following simpler change?
{code}
if (dirs.size() > 0) {
// randomize the first disk picked in the round-robin selection
dirNumLastAccessed = dirIndexRandomizer.nextInt(dirs.size());
}
{code}
then it will trigger {{DiskErrorException}} later due to zero length
{{localDirs}} if calling from {{getLocalPathForWrite}} or
{{getLocalPathToRead}} .
> getLocalPathForWrite is not throwing any expection for invalid paths
> --------------------------------------------------------------------
>
> Key: HADOOP-8437
> URL: https://issues.apache.org/jira/browse/HADOOP-8437
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs
> Affects Versions: 2.0.0-alpha, 2.6.0, 3.0.0
> Reporter: Brahma Reddy Battula
> Assignee: Brahma Reddy Battula
> Labels: BB2015-05-TBR
> Attachments: HADOOP-8437-003.patch, HADOOP-8437.patch,
> HADOOP-8437_1.patch, HADOOP-8437_2.patch
>
>
> call dirAllocator.getLocalPathForWrite ( "/InvalidPath", conf );
> Here it will not thrown any exception but earlier version it used throw.
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