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https://issues.apache.org/jira/browse/MAPREDUCE-7549?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Siyao Meng updated MAPREDUCE-7549:
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Status: Patch Available (was: Open)
> TaskAttemptImpl.isIP ignores IPv6 literals, so IPv6 split hosts lose data
> locality
> ----------------------------------------------------------------------------------
>
> Key: MAPREDUCE-7549
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-7549
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mr-am
> Reporter: Siyao Meng
> Assignee: Siyao Meng
> Priority: Minor
> Labels: ipv6
>
> [TaskAttemptImpl.java:1876|https://github.com/apache/hadoop/blob/1097744bc490b65cad5ab2fbeafff35687971357/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/TaskAttemptImpl.java#L1876]:
> {code:java}
> private static final Pattern ipPattern = // Pattern for matching ip
> Pattern.compile("\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}");
> {code}
> {{resolveHosts}} resolves IPv4 split hosts to host names through
> {{resolveHost}}, but passes IPv6 literals through unchanged. The NodeManager
> registers its host as {{getCanonicalHostName()}}: either the PTR name, or the
> full form {{2001:db8:0:0:0:0:0:21}}. A split host given as {{2001:db8::21}}
> matches neither. The RM scheduler and {{RMContainerAllocator}} match hosts as
> strings, so the request is never node-local, and the locality counters are
> wrong.
> This needs split hosts that are IPv6 literals, for example with
> {{dfs.datanode.hostname}} set to a literal or a non-HDFS {{InputFormat}}. The
> default DataNode host name uses the same {{getCanonicalHostName()}} form as
> the NodeManager. Nothing fails; only locality is lost.
> Verified by running the pattern and
> {{InetAddress.getByName(..).getHostName()}} on JDK 21; with no PTR record the
> result is the full form, which equals the NodeManager's host. Locality was
> not measured on a cluster.
> *Proposed fix:* use {{InetAddresses.isInetAddress(src)}} in {{isIP}}, so IPv6
> literals go through {{resolveHost}} like IPv4.
> Related to YARN-1226 (short name compared with FQDN), which has a different
> cause.
> POC:
> https://github.com/smengcl/hadoop/commit/f149887a2d7fc2ef9949d3daba413e9a1962fe55
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