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From "Zhe Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-8033) Erasure coding: stateful (non-positional) read from files in striped layout
Date Wed, 01 Apr 2015 17:25:53 GMT

    [ https://issues.apache.org/jira/browse/HDFS-8033?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14391026#comment-14391026
] 

Zhe Zhang commented on HDFS-8033:
---------------------------------

Thanks for the question Rui. Similar to UNIX, HDFS provides both _read_ and _pread_ semantics.
In a nutshell, _pread_ doesn't modify the state of the file descriptor, like the current position.
For example, when you do _read()_, _pread()_, _read()_, then second _read()_ will resume from
the position after the first _read()_.

Please also refer to [this | http://stackoverflow.com/questions/1687275/what-is-the-difference-between-read-and-pread-in-unix]

> Erasure coding: stateful (non-positional) read from files in striped layout
> ---------------------------------------------------------------------------
>
>                 Key: HDFS-8033
>                 URL: https://issues.apache.org/jira/browse/HDFS-8033
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: Zhe Zhang
>            Assignee: Zhe Zhang
>




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