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Date: Thu, 19 Dec 2013 20:50:04 +0800
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 <CAFHQjKyhKZHxatOG=5EKdR063Xg9G4Qnc=t=ydAWc-1JEWFW-w@mail.gmail.com>
Subject: Re: Why other process can't see the change after calling hdfsHFlush
 unless hdfsCloseFile is called?
From: Xiaobin She <xiaobinshe@gmail.com>
To: user@hadoop.apache.org
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sorry to reply to my own thread.

Does anyone know the answer to this question?
If so, can you please tell me if my understanding is right or wrong?

thanks.


2013/12/17 Xiaobin She <xiaobinshe@gmail.com>

> hi,
>
> I'm using libhdfs to deal with hdfs in an c++ programme.
>
> And I have encountered an problem.
>
> here is the scenario :
> 1. first I call hdfsOpenFile with O_WRONLY flag to open an file
> 2. call hdfsWrite to write some data
> 3. call hdfsHFlush to flush the data,  according to the header hdfs.h,
> after this call returns, new readers shoule be able to see the data
> 4. I use an http get request to get the file list on that directionary
> through the webhdfs interface,
> here  I have to use the webhdfs interface because I need to deal with
> symlink file
> 5. from the json response which is returned by the webhdfs, I found that
> the lenght of the file is still 0.
>
> I have tried to replace hdfsHFlush with hdfsFlush or hdfsSync, or call
> these three together, but still doesn't work.
>
> Buf if I call hdfsCloseFile after I call the hdfsHFlush, then I can get
> the correct file lenght through the webhdfs interface.
>
>
> Is this right? I mean if you want the other process to see the change  of
> data, you need to call hdfsCloseFile?
>
> Or is there somethings I did wrong?
>
> thank you very much for your help.
>
>
>
>
>

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<div dir=3D"ltr"><br>sorry to reply to my own thread.<br><br>Does anyone kn=
ow the answer to this question?<br>If so, can you please tell me if my unde=
rstanding is right or wrong?<br><br>thanks.<br><br></div><div class=3D"gmai=
l_extra">
<br><br><div class=3D"gmail_quote">2013/12/17 Xiaobin She <span dir=3D"ltr"=
>&lt;<a href=3D"mailto:xiaobinshe@gmail.com" target=3D"_blank">xiaobinshe@g=
mail.com</a>&gt;</span><br><blockquote class=3D"gmail_quote" style=3D"margi=
n:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir=3D"ltr">hi, <br><br>I&#39;m using libhdfs to deal with hdfs in an =
c++ programme.<br><br>And I have encountered an problem.<br><br>here is the=
 scenario :<br>1. first I call hdfsOpenFile with O_WRONLY flag to open an f=
ile<br>

2. call hdfsWrite to write some data<br>3. call hdfsHFlush to flush the dat=
a,=A0 according to the header hdfs.h, after this call returns, new readers =
shoule be able to see the data<br>4. I use an http get request to get the f=
ile list on that directionary through the webhdfs interface,<br>

here=A0 I have to use the webhdfs interface because I need to deal with sym=
link file<br>5. from the json response which is returned by the webhdfs, I =
found that the lenght of the file is still 0.<br><br>I have tried to replac=
e hdfsHFlush with hdfsFlush or hdfsSync, or call these three together, but =
still doesn&#39;t work.<br>

<br>Buf if I call hdfsCloseFile after I call the hdfsHFlush, then I can get=
 the correct file lenght through the webhdfs interface.<br><br><br>Is this =
right? I mean if you want the other process to see the change=A0 of data, y=
ou need to call hdfsCloseFile?<br>

<br>Or is there somethings I did wrong?<br><br>thank you very much for your=
 help.<br><br><br><br><br></div>
</blockquote></div><br></div>

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