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Posted to hdfs-issues@hadoop.apache.org by "dhruba borthakur (JIRA)" <ji...@apache.org> on 2011/02/01 19:40:29 UTC

[jira] Updated: (HDFS-1605) Convert DFSInputStream synchronized sections to a ReadWrite lock

     [ https://issues.apache.org/jira/browse/HDFS-1605?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

dhruba borthakur updated HDFS-1605:
-----------------------------------

    Attachment: DFSClientRWlock.3.txt

Merged patch with latest branch.

> Convert DFSInputStream synchronized sections to a ReadWrite lock
> ----------------------------------------------------------------
>
>                 Key: HDFS-1605
>                 URL: https://issues.apache.org/jira/browse/HDFS-1605
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: hdfs client
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>         Attachments: DFSClientRWlock.1.txt, DFSClientRWlock.3.txt
>
>
> Hbase does concurrent preads from multiple threads to different blocks of the same hdfs file. Each of these pread calls invoke DFSInputStream.getFileLength() and DFSInputStream.getBlockAt(). These methods are "synchronized", thus causing all the concurrent threads to serialize. It would help performance to convert this to a Read/Write lock

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