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Date: Wed, 26 Nov 2014 20:56:14 +0000 (UTC)
From: "Jing Zhao (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12757448.1416848953000.29899.1417035374020@Atlassian.JIRA>
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Subject: [jira] [Updated] (HDFS-7435) PB encoding of block reports is very
 inefficient
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     [ https://issues.apache.org/jira/browse/HDFS-7435?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jing Zhao updated HDFS-7435:
----------------------------
    Attachment: HDFS-7435.001.patch

Fix a bug in the demo patch.

> PB encoding of block reports is very inefficient
> ------------------------------------------------
>
>                 Key: HDFS-7435
>                 URL: https://issues.apache.org/jira/browse/HDFS-7435
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: datanode, namenode
>    Affects Versions: 2.0.0-alpha, 3.0.0
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>            Priority: Critical
>         Attachments: HDFS-7435.000.patch, HDFS-7435.001.patch, HDFS-7435.patch
>
>
> Block reports are encoded as a PB repeating long.  Repeating fields use an {{ArrayList}} with default capacity of 10.  A block report containing tens or hundreds of thousand of longs (3 for each replica) is extremely expensive since the {{ArrayList}} must realloc many times.  Also, decoding repeating fields will box the primitive longs which must then be unboxed.


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