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From "Wei-Chiu Chuang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-11661) GetContentSummary uses excessive amounts of memory
Date Tue, 23 May 2017 19:10:04 GMT

    [ https://issues.apache.org/jira/browse/HDFS-11661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16021680#comment-16021680
] 

Wei-Chiu Chuang commented on HDFS-11661:
----------------------------------------

Heads up I am going to revert both commits EOD. I believe I've got sufficient number of upvotes.

> GetContentSummary uses excessive amounts of memory
> --------------------------------------------------
>
>                 Key: HDFS-11661
>                 URL: https://issues.apache.org/jira/browse/HDFS-11661
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 2.8.0, 3.0.0-alpha2
>            Reporter: Nathan Roberts
>            Assignee: Wei-Chiu Chuang
>            Priority: Blocker
>         Attachments: HDFS-11661.001.patch, HDFs-11661.002.patch, Heap growth.png
>
>
> ContentSummaryComputationContext::nodeIncluded() is being used to keep track of all INodes
visited during the current content summary calculation. This can be all of the INodes in the
filesystem, making for a VERY large hash table. This simply won't work on large filesystems.

> We noticed this after upgrading a namenode with ~100Million filesystem objects was spending
significantly more time in GC. Fortunately this system had some memory breathing room, other
clusters we have will not run with this additional demand on memory.
> This was added as part of HDFS-10797 as a way of keeping track of INodes that have already
been accounted for - to avoid double counting.



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