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From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-6813) WebHdfsFileSystem#OffsetUrlInputStream should implement PositionedReadable with thead-safe.
Date Tue, 05 Aug 2014 08:45:12 GMT

    [ https://issues.apache.org/jira/browse/HDFS-6813?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14086007#comment-14086007
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Steve Loughran commented on HDFS-6813:
--------------------------------------

Nicholas, can you look at HADOOP-10938 and see if we can pull this discussion together.

For HBase they are looking at what could be done for concurrent HDFS operations, that is what
can be relaxed/unrelaxed.

The native IO streams are all generally wrapped by RawLocal and checksummed filesystems, so
they get their sync semantics from there.

What we do have, however is a model in which {{getPos() }} can block until a potentially remote,
long-haul IO operation completes, which I think is an anomaly.

> WebHdfsFileSystem#OffsetUrlInputStream should implement PositionedReadable with thead-safe.
> -------------------------------------------------------------------------------------------
>
>                 Key: HDFS-6813
>                 URL: https://issues.apache.org/jira/browse/HDFS-6813
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: webhdfs
>    Affects Versions: 2.6.0
>            Reporter: Yi Liu
>            Assignee: Yi Liu
>         Attachments: HDFS-6813.001.patch
>
>
> {{PositionedReadable}} definition requires the implementations for its interfaces should
be thread-safe.
> OffsetUrlInputStream(WebHdfsFileSystem inputstream) doesn't implement these interfaces
with tread-safe, this JIRA is to fix this.



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