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Date: Thu, 26 Feb 2009 11:37:02 -0800 (PST)
From: "dhruba borthakur (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Commented: (HADOOP-4379) In HDFS, sync() not yet guarantees
 data available to the new readers
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    [ https://issues.apache.org/jira/browse/HADOOP-4379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12677118#action_12677118 ] 

dhruba borthakur commented on HADOOP-4379:
------------------------------------------

There is ReopenProblem.java attched to this JIRA.

@Doug: Please use ReopenProblem.java:waitForLeaseRecovery(). This method triggers near-immediate lease recovery and can be used by any application code to take ownership of the file. Does this work for you?

@Jim: Were u using ReopenProblem.java:waitForLeaseRecovery() and still seeing that it takes upto an hour for the waitForLeaseRecovery() method to return success? This can happen if the original client that was writing to the file was alive and was in communication with the namenode. In this case, the new append-er will not be able to recover the original lease.

> In HDFS, sync() not yet guarantees data available to the new readers
> --------------------------------------------------------------------
>
>                 Key: HADOOP-4379
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4379
>             Project: Hadoop Core
>          Issue Type: New Feature
>          Components: dfs
>            Reporter: Tsz Wo (Nicholas), SZE
>            Assignee: dhruba borthakur
>            Priority: Blocker
>             Fix For: 0.19.2, 0.20.0
>
>         Attachments: 4379_20081010TC3.java, fsyncConcurrentReaders.txt, fsyncConcurrentReaders3.patch, fsyncConcurrentReaders4.patch, hypertable-namenode.log.gz, Reader.java, Reader.java, reopen_test.sh, ReopenProblem.java, Writer.java, Writer.java
>
>
> In the append design doc (https://issues.apache.org/jira/secure/attachment/12370562/Appends.doc), it says
> * A reader is guaranteed to be able to read data that was 'flushed' before the reader opened the file
> However, this feature is not yet implemented.  Note that the operation 'flushed' is now called "sync".

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