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https://issues.apache.org/jira/browse/HADOOP-803?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12466869
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Raghu Angadi commented on HADOOP-803:
-------------------------------------
Another relatively simpler change :
each Inode allocates a TreeMap for chidren. Each TreeMap takes around 40 bytes
(from profiler, not sure if it includes gc overhead). Since most nodes in FS
don't have any children, we can postpone allocating TreeMap until it is needed.
--- (a)
INode.children does not strictly need to be a TreeMap. Each TreeMap entry seems
to be around 30 bytes. I am not planning to include this change in this bug,
but that would be another 30 bytes per node.
> Reducing memory consumption on Namenode : Part 1
> ------------------------------------------------
>
> Key: HADOOP-803
> URL: https://issues.apache.org/jira/browse/HADOOP-803
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Reporter: Raghu Angadi
> Assigned To: Raghu Angadi
> Fix For: 0.11.0
>
> Attachments: block-refs-2.patch, block-refs-3.patch,
> block-refs-5.patch, HADOOP-803-2.patch, HADOOP-803.patch
>
>
> There appears to be some places in Namenode that allow reducing memory
> consumption without intrusive code or feature changes. This bug is an initial
> attempt making those changes. Please include your thoughts as well.
> One change I am planning to make :
> Currently one copy of each block exists for each of the replicas and one copy
> for blockMap. I think they are all supposed to be same.
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