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From "Doug Judd (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 22:11:02 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12677158#action_12677158
] 

Doug Judd commented on HADOOP-4379:
-----------------------------------

Hi Dhruba,

When you say "near-immediate" what does that mean?  Is it the 1 minute soft limit?  If so,
that's way too long.  If a node bounces in our cluster, we can't have the database locked
up for an entire minute waiting for the lease to expire when we know for a 100% fact that
the original leaseholder is dead.  A one minute database lock-up would make Hypertable unsuitable
for serving live data.

- Doug


> 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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