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HDFS, mail # dev - non-local map task input


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Grandl Robert 2013-07-22, 03:41
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Grandl Robert 2013-07-22, 17:06
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Re: non-local map task input
Colin Patrick McCabe 2013-07-25, 23:46
Try looking at DFSOutputStream / DFSInputStream.

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Colin
On Jul 21, 2013 8:41 PM, "Grandl Robert" <[EMAIL PROTECTED]> wrote:

> Hi guys,
>
> I am trying to figure out all the points in hdfs code where hdfs traffic
> is read/written. As far as I can tell, it seems most of the traffic goes
> through BlockSender/BlockReceiver, right ?
>
> However, when a client do a copyFromLocal, or read a file, or for a map
> task whose input is not local, it seems the DFSClient is invoked. I
> understand that with DFSClient, it gets the dananodes locations from
> namenode and then directly open a socket and read/writes. Anyway, I am not
> very sure where that happens. Can someone point me out where in the code I
> can find the exact calls to read/write from other datanodes with DFSClient ?
>
> Thanks in advance,
> Robert