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https://issues.apache.org/jira/browse/HDFS-6268?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrew Wang reopened HDFS-6268:
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Looks like branch-2 needs a different patch, since it has an extra test file
that needs to be updated.
> Better sorting in NetworkTopology#pseudoSortByDistance when no local node is
> found
> ----------------------------------------------------------------------------------
>
> Key: HDFS-6268
> URL: https://issues.apache.org/jira/browse/HDFS-6268
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 2.4.0
> Reporter: Andrew Wang
> Assignee: Andrew Wang
> Priority: Minor
> Fix For: 3.0.0
>
> Attachments: hdfs-6268-1.patch, hdfs-6268-2.patch, hdfs-6268-3.patch,
> hdfs-6268-4.patch, hdfs-6268-5.patch
>
>
> In NetworkTopology#pseudoSortByDistance, if no local node is found, it will
> always place the first rack local node in the list in front.
> This became an issue when a dataset was loaded from a single datanode. This
> datanode ended up being the first replica for all the blocks in the dataset.
> When running an Impala query, the non-local reads when reading past a block
> boundary were all hitting this node, meaning massive load skew.
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