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From He Chen <airb...@gmail.com>
Subject Re: Hadoop's deafult FIFO scheduler
Date Fri, 15 Oct 2010 10:11:49 GMT
Hi Hemanth

all jobs were submitted within a minute and a few
seconds between jobs. The hadoop version is 0.20.2

Thanks


On Thu, Oct 14, 2010 at 11:45 PM, Hemanth Yamijala <yhemanth@gmail.com>wrote:

> Hi,
>
> On Thu, Oct 14, 2010 at 10:59 PM, He Chen <airbots@gmail.com> wrote:
> > they arrived in 1 minute. I understand there will be a setup phase which
> > will use any free slot no matter map or reduce.
> >
>
> You mean all jobs were submitted within a minute ? That means a few
> seconds between jobs ? Or do you mean each job was submitted a minute
> after the earlier job. Also, which version of Hadoop is this ?
>
> > 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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