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Date: Thu, 14 Oct 2010 13:15:40 -0500
Message-ID: <AANLkTinpUwz9bp7Wc24-=3uorPVBQhY7v+pQpe-j+-GN@mail.gmail.com>
Subject: Re: Hadoop's deafult FIFO scheduler
From: He Chen <airbots@gmail.com>
To: common-dev@hadoop.apache.org
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I doubt this. According to the execution record. the disk and network
utilization are the same.

At last, if the FCFS scheduler only apply for the setup stage which takes
about several second. This does not mean anything. users who submit their
jobs earlier only ge job setup earlier, but may be delayed for any possible
hardware and software reason? Acutally, most of the job can be finished
following the FIFO sequence. What I am curious is about why some one get in
the FIFO queue at the start point. What is the reason?

On Thu, Oct 14, 2010 at 12:50 PM, Nan Zhu <zhunansjtu@gmail.com> wrote:

> Hi, Chen
>
> I think it's due to the disk/network performance, I mean the speed of
> reading the content on disk/network into the local memory
>
>  if job3 hasn't complete data to start mappers, but job4 does, the
> scheduler
> would select the tasks of job4 from the list to run firstly,
>
> I think the so called FIFO principle is intended to setup stage, the
> firstly
> arrived job would be setup firstly
>
> Nan
>
>
>
> On Fri, Oct 15, 2010 at 1:29 AM, 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.
> >
> > 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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