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Date: Thu, 14 Apr 2011 19:12:05 +0000 (UTC)
From: "Hairong Kuang (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
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Subject: [jira] [Updated] (HDFS-1070) Speedup NameNode image loading and
 saving by storing local file names
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     [ https://issues.apache.org/jira/browse/HDFS-1070?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hairong Kuang updated HDFS-1070:
--------------------------------

    Attachment: trunkLocalNameImage9.patch

re-submitting to trigger hudson.

> Speedup NameNode image loading and saving by storing local file names
> ---------------------------------------------------------------------
>
>                 Key: HDFS-1070
>                 URL: https://issues.apache.org/jira/browse/HDFS-1070
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: name-node
>            Reporter: Hairong Kuang
>            Assignee: Hairong Kuang
>             Fix For: 0.23.0
>
>         Attachments: trunkLocalNameImage.patch, trunkLocalNameImage1.patch, trunkLocalNameImage3.patch, trunkLocalNameImage4.patch, trunkLocalNameImage5.patch, trunkLocalNameImage6.patch, trunkLocalNameImage7.patch, trunkLocalNameImage8.patch, trunkLocalNameImage9.patch, trunkLocalNameImage9.patch
>
>
> Currently each inode stores its full path in the fsimage. I'd propose to store the local name instead. In order for each inode to identify its parent, all inodes in a directory tree are stored in the image in in-order. This proposal also requires each directory stores the number of its children in image.
> This proposal would bring a few benefits as pointed below and therefore speedup the image loading and saving.
> # Remove the overhead of converting java-UTF8 encoded local name to string-represented full path then to UTF8 encoded full path when saving to an image and vice versa when loading the image.
> # Remove the overhead of traversing the full path when inserting the inode to its parent inode.
> # Reduce the number of temporary java objects during the process of image loading or saving and  therefore reduce the GC overhead.
> # Reduce the size of an image.

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