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From abhishek sharma <absha...@usc.edu>
Subject Re: Hadoop's deafult FIFO scheduler
Date Thu, 14 Oct 2010 17:10:42 GMT
What is the inter-arrival time between these jobs?

There is a "set up" phase for jobs before they are launched. It is
possible that the order of jobs can change due to slightly different
set up times. Apart from the number of blocks, it may matter "where"
these blocks lie.

Abhishek

On Thu, Oct 14, 2010 at 10:06 AM, He Chen <airbots@gmail.com> wrote:
> Hi all
>
> I am testing the performance of my Hadoop clsuters with Hadoop Default FIFO
> schedular. But I find a interesting phenomina.
>
> When I submit a series of jobs, some job will be executed earlier even they
> are submitted late. All jobs are request same amount of blocks. For example:
> job 1  submit at time 0
> job 2 submit at time 1
> job 3 submit at time 2
> job 4 submit at time 3
>
>
> job 4 's queue time is smaller than job3's queue time. This disobey the FIFO
> principle. Any one can give a hint?
>
> Thanks
>
> Chen
>

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