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https://issues.apache.org/jira/browse/HDFS-1392?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13012784#comment-13012784
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Matt Foley commented on HDFS-1392:
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It seems like the real goal (fixing the scalability problem due to lost
heartbeats during cluster startup) was achieved in a different, simpler way by
HDFS-1541.
> Improve namenode scalability by prioritizing datanode heartbeats over block
> reports
> -----------------------------------------------------------------------------------
>
> Key: HDFS-1392
> URL: https://issues.apache.org/jira/browse/HDFS-1392
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: name-node
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
>
> When a namenode restarts, it gets heartbeats followed by a block reports from
> the datanodes. The block report processing is heavyweight and can take many
> many seconds, especially when the number of blocks in each datanode is large.
> This causes the namenode to not be able to process heartbeats in time, thus
> leading to "lost heartbeats from datanode". The namenode declares the
> datanode to be dead and the datanode has to re-send its register/block report
> all over again. This is a scalability problem.
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