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MapReduce, mail # user - partition as block?


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Re: partition as block?
Mohammad Tariq 2013-04-30, 18:56
Hello Jay,

    What are you going to do in your custom InputFormat and partitioner?Is
your InputFormat is going to create larger splits which will overlap with
larger blocks?If that is the case, IMHO, then you are going to reduce the
no. of mappers thus reducing the parallelism. Also, much larger block size
will put extra overhead when it comes to disk I/O.

Warm Regards,
Tariq
https://mtariq.jux.com/
cloudfront.blogspot.com
On Wed, May 1, 2013 at 12:16 AM, Jay Vyas <[EMAIL PROTECTED]> wrote:

> Hi guys:
>
> Im wondering - if I'm running mapreduce jobs on a cluster with large block
> sizes - can i increase performance with either:
>
> 1) A custom FileInputFormat
>
>  2) A custom partitioner
>
> 3) -DnumReducers
>
> Clearly, (3) will be an issue due to the fact that it might overload tasks
> and network traffic... but maybe (1) or (2) will be a precise way to "use"
> partitions as a "poor mans" block.
>
> Just a thought - not sure if anyone has tried (1) or (2) before in order
> to simulate blocks and increase locality by utilizing the partition API.
>
> --
> Jay Vyas
> http://jayunit100.blogspot.com
>