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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4379) In HDFS, sync() not yet guarantees data available to the new readers
Date Tue, 26 May 2009 23:03:45 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12713316#action_12713316

stack commented on HADOOP-4379:

After a chat with Hairong and Dhruba, it was thought that the wait on a successful append,
close, then open to read was not necessary in this patch; that a new reader should be able
to read up to the dead writers last sync.  I tried it and all I get are EOFs when the new
reader tries to read the dead writers file.

> 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
>         Attachments: 4379_20081010TC3.java, fsyncConcurrentReaders.txt, fsyncConcurrentReaders3.patch,
fsyncConcurrentReaders4.patch, fsyncConcurrentReaders5.txt, fsyncConcurrentReaders6.patch,
fsyncConcurrentReaders9.patch, hypertable-namenode.log.gz, namenode.log, namenode.log, 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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