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Date: Wed, 20 Jul 2011 19:02:58 +0000 (UTC)
From: "Uma Maheswara Rao G (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
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Subject: [jira] [Commented] (HDFS-1774) Small optimization to FSDataset
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    [ https://issues.apache.org/jira/browse/HDFS-1774?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13068564#comment-13068564 ] 

Uma Maheswara Rao G commented on HDFS-1774:
-------------------------------------------

Thanks a lot for Nicholas and Eli for Review :-)

> Small optimization to FSDataset
> -------------------------------
>
>                 Key: HDFS-1774
>                 URL: https://issues.apache.org/jira/browse/HDFS-1774
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: data-node
>            Reporter: Uma Maheswara Rao G
>            Assignee: Uma Maheswara Rao G
>            Priority: Minor
>             Fix For: 0.23.0
>
>         Attachments: HDFS-1774-1.patch, HDFS-1774-1.patch, HDFS-1774.patch
>
>
>  Inner class FSDir constructor is doing duplicate iterations over the listed files in the passed directory. We can optimize this to single loop and also we can avoid isDirectory check which will perform some native invocations. 
>   Consider a case: one directory has only one child directory and 10000 files. 
> 1) First loop will get the number of children directories.
> 2) if (numChildren > 0) , This condition will satisfy and again it will iterate 10001 times and also will check isDirectory.

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