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https://issues.apache.org/jira/browse/HDFS-10208?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ming Ma updated HDFS-10208:
---------------------------
Attachment: HDFS-10208-2.patch
The new patch will take care of the case where {{DNSToSwitchMapping}} returns
{{NetworkTopology.DEFAULT_RACK}}, which means it can't resolve network path. In
addition, even if the client machine is able to resolve its network location,
some applications might not care about these bytes-read-by-distance metrics.
Given there is additional cost with this feature such as script launch, extra
memory for topology object, the new patch also added a new config to allow
applications to enable the feature.
> Addendum for HDFS-9579: to handle the case when client machine can't resolve
> network path
> -----------------------------------------------------------------------------------------
>
> Key: HDFS-10208
> URL: https://issues.apache.org/jira/browse/HDFS-10208
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Ming Ma
> Assignee: Ming Ma
> Attachments: HDFS-10208-2.patch, HDFS-10208.patch
>
>
> If DFSClient runs on a machine that can't resolve network path,
> e.g.{{dnsToSwitchMapping.resolve}} returns null, that will cause exception
> when it tries to create {{clientNode}}. In such case, there is no need to
> create {{clientNode}} as null {{clientNode}} means its network distance with
> any datanode is Integer.MAX_VALUE, which is what we want.
> {noformat}
> clientNode = new NodeBase(clientHostName,
> dnsToSwitchMapping.resolve(nodes).get(0));
> {noformat}
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