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Posted to common-issues@hadoop.apache.org by "Hudson (JIRA)" <ji...@apache.org> on 2010/02/02 07:18:20 UTC
[jira] Commented: (HADOOP-1126) Optimize CPU usage when cluster
restarts
[ https://issues.apache.org/jira/browse/HADOOP-1126?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12828478#action_12828478 ]
Hudson commented on HADOOP-1126:
--------------------------------
Integrated in Hadoop-Mapreduce-trunk-Commit #225 (See [http://hudson.zones.apache.org/hudson/job/Hadoop-Mapreduce-trunk-Commit/225/])
> Optimize CPU usage when cluster restarts
> ----------------------------------------
>
> Key: HADOOP-1126
> URL: https://issues.apache.org/jira/browse/HADOOP-1126
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 0.12.0
> Reporter: dhruba borthakur
> Assignee: Hairong Kuang
> Fix For: 0.12.1
>
> Attachments: neededReplicationRemove.patch
>
>
> When the namenode restarts, all datanodes report their blocks to the namenode. The namenode inserts these blocks into neededReplication(). When safemode exists, pendingTransfers removes them from neededReplication. This is non-optimal because pendingTransfer consumes plenty of CPU just after exiting safe-mode.
> The problem is that neededReplications.remove(block) does not remove a block if oldExpectedReplicas is exactly equal to oldReplicas.
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