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https://issues.apache.org/jira/browse/HBASE-5259?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13194469#comment-13194469
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Phabricator commented on HBASE-5259:
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tedyu has commented on the revision "[jira][HBASE-5259] Normalize the
RegionLocation in TableInputFormat by the reverse DNS lookup.".
INLINE COMMENTS
src/main/java/org/apache/hadoop/hbase/mapreduce/TableInputFormatBase.java:202
I think NamingException handling @ line 166 should be moved here.
REVISION DETAIL
https://reviews.facebook.net/D1413
> Normalize the RegionLocation in TableInputFormat by the reverse DNS lookup.
> ---------------------------------------------------------------------------
>
> Key: HBASE-5259
> URL: https://issues.apache.org/jira/browse/HBASE-5259
> Project: HBase
> Issue Type: Improvement
> Reporter: Liyin Tang
> Assignee: Liyin Tang
> Attachments: D1413.1.patch, D1413.1.patch, D1413.1.patch,
> D1413.1.patch, D1413.2.patch, D1413.2.patch, D1413.2.patch, D1413.2.patch,
> D1413.3.patch, D1413.3.patch, D1413.3.patch, D1413.3.patch
>
>
> Assuming the HBase and MapReduce running in the same cluster, the
> TableInputFormat is to override the split function which divides all the
> regions from one particular table into a series of mapper tasks. So each
> mapper task can process a region or one part of a region. Ideally, the mapper
> task should run on the same machine on which the region server hosts the
> corresponding region. That's the motivation that the TableInputFormat sets
> the RegionLocation so that the MapReduce framework can respect the node
> locality.
> The code simply set the host name of the region server as the
> HRegionLocation. However, the host name of the region server may have
> different format with the host name of the task tracker (Mapper task). The
> task tracker always gets its hostname by the reverse DNS lookup. And the DNS
> service may return different host name format. For example, the host name of
> the region server is correctly set as a.b.c.d while the reverse DNS lookup
> may return a.b.c.d. (With an additional doc in the end).
> So the solution is to set the RegionLocation by the reverse DNS lookup as
> well. No matter what host name format the DNS system is using, the
> TableInputFormat has the responsibility to keep the consistent host name
> format with the MapReduce framework.
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