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Date: Tue, 23 Feb 2010 21:49:28 +0000 (UTC)
From: "Hairong Kuang (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Subject: [jira] Updated: (HDFS-946) NameNode should not return full path
 name when lisitng a diretory or getting the status of a file
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     [ https://issues.apache.org/jira/browse/HDFS-946?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hairong Kuang updated HDFS-946:
-------------------------------

    Attachment: HdfsFileStatusProxy-Yahoo20.patch

This patch additionally has the change to hdfsproxy in Yahoo!'s security branch.

> NameNode should not return full path name when lisitng a diretory or getting the status of a file
> -------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-946
>                 URL: https://issues.apache.org/jira/browse/HDFS-946
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: Hairong Kuang
>            Assignee: Hairong Kuang
>             Fix For: 0.22.0
>
>         Attachments: HdfsFileStatus-yahoo20.patch, HDFSFileStatus.patch, HDFSFileStatus1.patch, HdfsFileStatus3.patch, HdfsFileStatus4.patch, HdfsFileStatusProxy-Yahoo20.patch
>
>
> FSDirectory#getListring(String src) has the following code:
>       int i = 0;
>       for (INode cur : contents) {
>         listing[i] = createFileStatus(srcs+cur.getLocalName(), cur);
>         i++;
>       }
> So listing a directory will return an array of FileStatus. Each FileStatus element has the full path name. This increases the return message size and adds non-negligible CPU time to the operation.
> FSDirectory#getFileInfo(String) does not need to return the file name either.
> Another optimization is that in the version of FileStatus that's used in the wire protocol, the field path does not need to be Path; It could be a String or a byte array ideally. This could avoid unnecessary creation of the Path objects at NameNode, thus help reduce the GC problem observed when a large number of getFileInfo or getListing operations hit NameNode.

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