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https://issues.apache.org/jira/browse/HADOOP-842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12462377
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Hairong Kuang commented on HADOOP-842:
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Thanks Doug for your suggestion.
I realized that passing the datanode port # as a part of clientMachine is not a
good idea. When a datanode starts up, it tries to use the port from
conf.get("dfs.datanode.port"). But if there is a failure, it tries a different
port#. So it is not right that a dfs client simply assumes that the local
datanode has the port# of conf.get("dfs.datanode.port").
I'd like to change the open method so that parameter clientMachine contains
only hostName but no port#. At the name node side, the datanode list will be
searched based on hostname not hostname:port#.
> change the open method in ClientProtocol to take an additional argument:
> clientMachine
> --------------------------------------------------------------------------------------
>
> Key: HADOOP-842
> URL: https://issues.apache.org/jira/browse/HADOOP-842
> Project: Hadoop
> Issue Type: Improvement
> Components: dfs
> Affects Versions: 0.9.2
> Reporter: Hairong Kuang
> Assigned To: Hairong Kuang
> Fix For: 0.10.0
>
> Attachments: open.patch
>
>
> The open method returns a list of blocks that belong to a file and, for each
> block, a list of datanodes that contain the block.To improve reading
> efficiency, I'd like to return the list of datanodes in the order of its
> distance to the client machine. So I suggest that we make the open method to
> take an additional argument clientMachine which is in the format of
> hostname:port#.
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