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Date: Mon, 12 Nov 2007 17:51:50 -0800 (PST)
From: "Christian Kunz (JIRA)" <jira@apache.org>
To: hadoop-dev@lucene.apache.org
Subject: [jira] Updated: (HADOOP-713) dfs list operation is too expensive
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     [ https://issues.apache.org/jira/browse/HADOOP-713?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Christian Kunz updated HADOOP-713:
----------------------------------

    Priority: Blocker  (was: Major)

Changing to blocker based on conversation with Sameer.

> dfs list operation is too expensive
> -----------------------------------
>
>                 Key: HADOOP-713
>                 URL: https://issues.apache.org/jira/browse/HADOOP-713
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: dfs
>    Affects Versions: 0.8.0
>            Reporter: Hairong Kuang
>            Assignee: Hairong Kuang
>            Priority: Blocker
>
> A list request to dfs returns an array of DFSFileInfo. A DFSFileInfo of a directory contains a field called contentsLen, indicating its size  which gets computed at the namenode side by resursively going through its subdirs. At the same time, the whole dfs directory tree is locked.
> The list operation is used a lot by DFSClient for listing a directory, getting a file's size and # of replicas, and getting the size of dfs. Only the last operation needs the field contentsLen to be computed.
> To reduce its cost, we can add a flag to the list request. ContentsLen is computed If the flag is set. By default, the flag is false.

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