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https://issues.apache.org/jira/browse/HADOOP-1256?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12488735
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Raghu Angadi commented on HADOOP-1256:
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Just adding to the discussion :
> These bugs are related to the optimization issue HADOOP-971, which introduced
> a new data-structure in the name-node in order to accelerate access to
> data-nodes by name.
> It involves more complexity in synchronizing the new map with the other
> structures.
> We still don't know what the benefits are.
Would this bug be any easier to find or fix if this was introduced as part of
an feature improvement? Or do you think optimization patches tend to get less
rigorously tested and reviewed?
In some cases, performance improvements are really obvious even just by looking
at the code. I do not want to take credit for any part of HADOOP-971, but looks
like it was tested to show improvement.
> Dfs image loading and edits loading creates multiple instances of
> DatanodeDescriptor for the same datanode
> ----------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-1256
> URL: https://issues.apache.org/jira/browse/HADOOP-1256
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.12.3
> Reporter: Hairong Kuang
> Assigned To: Hairong Kuang
> Fix For: 0.13.0
>
> Attachments: nodeMap.patch
>
>
> This leads to multiple instances of DatanodeDescriptors for the same datanode
> stored in Host2DatanodeMap.
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