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https://issues.apache.org/jira/browse/HADOOP-1117?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tom White updated HADOOP-1117:
------------------------------

    Resolution: Fixed
        Status: Resolved  (was: Patch Available)

I've just committed this. Thanks Dhruba!

> DFS Scalability: When the namenode is restarted it consumes 80% CPU
> -------------------------------------------------------------------
>
>                 Key: HADOOP-1117
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1117
>             Project: Hadoop
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.12.0
>            Reporter: dhruba borthakur
>         Assigned To: dhruba borthakur
>            Priority: Blocker
>             Fix For: 0.12.1
>
>         Attachments: CpuPendingTransfer3.patch
>
>
> When the namenode is restarted, the datanodes register and each block is 
> inserted into neededReplication. When the namenode exists, safemode it sees 
> starts processing neededReplication. It picks up a block from 
> neededReplication, sees that it has already has the required number of 
> replicas, and continues to the next block in neededReplication. The blocks 
> remain in neededReplication permanentlyhe namenode worker thread to scans 
> this huge list of blocks once every 3 seconds. This consumes plenty of CPU on 
> the namenode.

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