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https://issues.apache.org/jira/browse/HDFS-611?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12753883#action_12753883
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Doug Cutting commented on HDFS-611:
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> Why is the heartbeat thread involved with block deletion?
The namenode returns lists of blocks to delete in heartbeat responses.
> The Nameode will think that the datanode has this block whereas actually it
> is now gone from the datanode.
The datanode might remove blocks immediately from its in-memory lists that are
used to generate block reports but the background thread could remove the
actual block files. If the datanode crashes then the discrepancy between
what's on disk and what the namenode thinks should be on disk will be resolved
at restart when it sends its initial block report. Could that work?
> Heartbeats times from Datanodes increase when there are plenty of blocks to
> delete
> ----------------------------------------------------------------------------------
>
> Key: HDFS-611
> URL: https://issues.apache.org/jira/browse/HDFS-611
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: data-node
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
>
> I am seeing that when we delete a large directory that has plenty of blocks,
> the heartbeat times from datanodes increase significantly from the normal
> value of 3 seconds to as large as 50 seconds or so. The heartbeat thread in
> the Datanode deletes a bunch of blocks sequentially, this causes the
> heartbeat times to increase.
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