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https://issues.apache.org/jira/browse/HDFS-6658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14357672#comment-14357672
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Charles Lamb commented on HDFS-6658:
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Hi [~daryn],
Colin and I read over the design doc. I confess that I still need to read over
the patch, but I will do that. Do you think it will be possible to create a
safe mode to run this in so that inconsistencies can be detected? I'm also
wondering what the field widths are, but I can find those when I read the patch.
> 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, HDFS-6658.patch, HDFS-6658.patch, Namenode
> Memory Optimizations - Block replicas list.docx, New primative indexes.jpg,
> Old triplets.jpg
>
>
> 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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