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https://issues.apache.org/jira/browse/HDFS-6658?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Daryn Sharp updated HDFS-6658:
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Attachment: BlocksMap redesign.pdf
For months I've been adapting the concepts of Amir's work, and extensively
profiling implementations. Here is a rough design doc that describes a working
implementation. I'll post a patch, hopefully this afternoon, after rebasing
on trunk.
> Namenode memory optimization - Block replicas list
> ---------------------------------------------------
>
> Key: HDFS-6658
> URL: https://issues.apache.org/jira/browse/HDFS-6658
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 2.4.1
> Reporter: Amir Langer
> Assignee: Daryn Sharp
> Attachments: BlockListOptimizationComparison.xlsx, BlocksMap
> redesign.pdf, HDFS-6658.patch, Namenode Memory Optimizations - Block replicas
> list.docx
>
>
> Part of the memory consumed by every BlockInfo object in the Namenode is a
> linked list of block references for every DatanodeStorageInfo (called
> "triplets").
> We propose to change the way we store the list in memory.
> Using primitive integer indexes instead of object references will reduce the
> memory needed for every block replica (when compressed oops is disabled) and
> in our new design the list overhead will be per DatanodeStorageInfo and not
> per block replica.
> see attached design doc. for details and evaluation results.
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