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From "Hairong Kuang (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-1126) Optimize CPU usage when cluster restarts
Date Fri, 16 Mar 2007 23:35:09 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-1126?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Hairong Kuang updated HADOOP-1126:
----------------------------------

    Attachment: neededReplicationRemove.patch

This patch fixed the described problem. It also changed the name of the class by incorporating
the suggestion in HADOOP-1026.

I tested the patch at a one-node cluster and saw 0 block in the underReplicatedBlocks when
the namenode restarted and left the safe mode.

> Optimize CPU usage when cluster restarts
> ----------------------------------------
>
>                 Key: HADOOP-1126
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1126
>             Project: Hadoop
>          Issue Type: Bug
>          Components: dfs
>            Reporter: dhruba borthakur
>         Assigned To: Hairong Kuang
>         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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