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From He Chen <airb...@gmail.com>
Subject Re: Hadoop's deafult FIFO scheduler
Date Thu, 14 Oct 2010 17:29:54 GMT
they arrived in 1 minute. I understand there will be a setup phase which
will use any free slot no matter map or reduce.

My queue time is the period between the start of Map stage and the time job
is submitted. Because the setup phase has the higher priority than map and
reduce tasks. Any job submitted in the queue will setup no matter how many
previous map and reduce tasks need to be assigned.

Now, I am sure the job3 setup stage finished earlier than job4's. However,
job3's map stage start later than job4's. BTW, they request same amount of
blocks.


On Thu, Oct 14, 2010 at 12:10 PM, abhishek sharma <absharma@usc.edu> wrote:

> 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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