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Date: Mon, 7 Nov 2011 15:42:51 +0000 (UTC)
From: "Todd Lipcon (Commented) (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
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Subject: [jira] [Commented] (HDFS-989) Flush/sync do not work on Hadoop
 LocalFileSystem
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    [ https://issues.apache.org/jira/browse/HDFS-989?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13145563#comment-13145563 ] 

Todd Lipcon commented on HDFS-989:
----------------------------------

With hsync/hflush at a checksum boundary, we re-write the last checksum into the checksum file at the same time as we append the new data. There is a race during which the new data is there but not the checksum info -- but during recovery operations I believe we deal with this situation by ignoring checksum errors on the last checksum-chunk if there are no replicas with a valid last-chunk.
                
> Flush/sync do not work on Hadoop LocalFileSystem
> ------------------------------------------------
>
>                 Key: HDFS-989
>                 URL: https://issues.apache.org/jira/browse/HDFS-989
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 0.20.1
>            Reporter: Nathan Marz
>
> They seem to be no-ops. This is really easy to reproduce, just open a file using FileSystem/getLocal(new Configuration()), write data to the output stream, and then try to flush/sync. I also tried creating the output stream with a buffer size of 1, but that had no effect.

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