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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 21:39:02 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12677151#action_12677151
] 

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

What is the value of leaseRecoveryPeriod in the above piece of code?

The fact that the lease recovery took 1 hour is very interesting. The namenode has two limits:
the soft limit of 1 minute and the hard limit of 1 hour. When there is no ping from a writer
for the soft limit period, then a new writer can recover the lease and append to the file.
When there is no ping from a writer for the hard limit period, the namenode itself itself
initiates lease recovery.

Is it possible for you to give me access to the namenode log along with the relevant filename
in question? 

> 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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