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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4379) In HDFS, sync() not yet guarantees data available to the new readers
Date Thu, 26 Feb 2009 19:37:02 GMT

    [ 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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