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https://issues.apache.org/jira/browse/HDFS-1605?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14544555#comment-14544555
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Ravi Prakash commented on HDFS-1605:
------------------------------------

Kartheek! Thanks. I also did not look through all possible cases of new race 
conditions. Did you?

> 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: kartheek muthyala
>              Labels: BB2015-05-RFC
>         Attachments: DFSClientRWlock.1.txt, DFSClientRWlock.3.txt, 
> HADOOP-1605-trunk-1.patch, HADOOP-1605-trunk.patch, HDFS-1605.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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