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Hadoop, mail # dev - Hadoop's deafult FIFO scheduler


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Re: Hadoop's deafult FIFO scheduler
Hemanth Yamijala 2010-10-15, 04:45
Hi,

On Thu, Oct 14, 2010 at 10:59 PM, He Chen <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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
>> >
>>
>