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Date: Thu, 9 Jun 2011 08:15:59 +0000 (UTC)
From: "Kihwal Lee (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
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Subject: [jira] [Commented] (HDFS-941) Datanode xceiver protocol should
 allow reuse of a connection
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    [ https://issues.apache.org/jira/browse/HDFS-941?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13046387#comment-13046387 ] 

Kihwal Lee commented on HDFS-941:
---------------------------------

It's read-only and yes it's against TRUNK. I put 200 X 170MB files across 8 DNs, dfs.replication=1. There are 200 random readers who are randomly reading from all 200 files. The locality was intentionally reduced to test the socket caching.  I will try a R/W test once this one is done.

> Datanode xceiver protocol should allow reuse of a connection
> ------------------------------------------------------------
>
>                 Key: HDFS-941
>                 URL: https://issues.apache.org/jira/browse/HDFS-941
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: data-node, hdfs client
>    Affects Versions: 0.22.0
>            Reporter: Todd Lipcon
>            Assignee: bc Wong
>         Attachments: HDFS-941-1.patch, HDFS-941-2.patch, HDFS-941-3.patch, HDFS-941-3.patch, HDFS-941-4.patch, HDFS-941-5.patch, HDFS-941-6.22.patch, HDFS-941-6.patch, HDFS-941-6.patch, HDFS-941-6.patch, hdfs-941.txt, hdfs-941.txt, hdfs-941.txt, hdfs941-1.png
>
>
> Right now each connection into the datanode xceiver only processes one operation.
> In the case that an operation leaves the stream in a well-defined state (eg a client reads to the end of a block successfully) the same connection could be reused for a second operation. This should improve random read performance significantly.

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