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HDFS, mail # user - Reading while appending in 0.21


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Re: Reading while appending in 0.21
Konstantin Boudnik 2010-01-12, 01:15
Jean,

I believe this is how it has been intended to work. If you take a look at the
test src/test/hdfs/org/apache/hadoop/hdfs/TestHFlush.java in HDFS workspace
you'll a comment on this particular aspect in the line 124.

Hope it helps,
   Cos

On 1/11/10 16:42 , Jean-Daniel Cryans wrote:
> Hi,
>
> I'm trying to use the new hflush function from 0.21 so that a
> SequenceFile.Reader could read edits from a SequenceFile.Writer after
> a signal on a Condition. If I:
>
> create the Writer
> append entries
> hflush
> create the Reader
> next() through the entries
>
> It works fine. But after that if I only next(), using the same reader,
> after appending/hflush I won't see the new edits. But, if I create a
> new Reader after calling hflush, it works fine.
>
> So this does not work:
>
> create the Writer
> append entries
> hflush
> create the Reader
> next() through the entries
> append entries
> hflush
> next() through the entries
> append entries
> hflush
> next() through the entries
>
> This does:
>
> create the Writer
> append entries
> hflush
> create the Reader
> next() through the entries
> append entries
> hflush
> create a new Reader
> seek
> next() through the entries
>
> Is that the intended behavior?
>
> Thx!
>
> J-D