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https://issues.apache.org/jira/browse/HDFS-14882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16956330#comment-16956330
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Íñigo Goiri commented on HDFS-14882:
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Given that consider load is already available for writes we should try to be as
consistent as possible.
In addition, we should be specific on the setting to avoid confusion.
For example, let's call the variable in DatanodeManager {{readConsiderLoad}}.
In addition, the key probably should be more generic and include "READ" instead
of "BLOCKLOCATION".
We may also want to tune the description for
"dfs.namenode.redundancy.considerLoad" to be more precise.
> Consider DataNode load when #getBlockLocation
> ---------------------------------------------
>
> Key: HDFS-14882
> URL: https://issues.apache.org/jira/browse/HDFS-14882
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Xiaoqiao He
> Assignee: Xiaoqiao He
> Priority: Major
> Attachments: HDFS-14882.001.patch, HDFS-14882.002.patch,
> HDFS-14882.003.patch, HDFS-14882.004.patch, HDFS-14882.005.patch,
> HDFS-14882.006.patch
>
>
> Currently, we consider load of datanode when #chooseTarget for writer,
> however not consider it for reader. Thus, the process slot of datanode could
> be occupied by #BlockSender for reader, and disk/network will be busy
> workload, then meet some slow node exception. IIRC same case is reported
> times. Based on the fact, I propose to consider load for reader same as it
> did #chooseTarget for writer.
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