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Date: Wed, 8 Jun 2011 19:25:59 +0000 (UTC)
From: "stack (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=13046148#comment-13046148 ] 

stack commented on HDFS-941:
----------------------------

+1 on commit.  Have run this patch first in a "light" random read loading over night and then over this morning with a 'heavy' random read + write loading on 5 node cluster.  Discernible perf improvement (caching involved so hard to say for sure but I see 20% improvement if just random reads).

@Kihwal Fair enough.

> 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.patch, HDFS-941-6.patch, HDFS-941-6.patch, 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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