Mailing-List: contact hdfs-issues-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: hdfs-issues@hadoop.apache.org
Date: Wed, 6 Apr 2011 03:07:05 +0000 (UTC)
From: "Tsz Wo (Nicholas), SZE (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: 
 <1433559656.36857.1302059225979.JavaMail.tomcat@hel.zones.apache.org>
Subject: [jira] [Commented] (HDFS-1070) Speedup NameNode image loading and
 saving by storing local file names
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/HDFS-1070?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13016225#comment-13016225 ] 

Tsz Wo (Nicholas), SZE commented on HDFS-1070:
----------------------------------------------

BTW, I am not saying that we should do the usernames/groups improvement in this JIRA.  Just want to express the idea.  See if anyone likes to try it later.

> 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
>         Attachments: trunkLocalNameImage.patch, trunkLocalNameImage1.patch, trunkLocalNameImage3.patch, trunkLocalNameImage4.patch, trunkLocalNameImage5.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.

--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira