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Subject: Re: Can't achieve load distribution
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From: Anil Gupta <anilgupta84@gmail.com>
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Date: Wed, 1 Feb 2012 17:44:29 -0800
To: "common-user@hadoop.apache.org" <common-user@hadoop.apache.org>
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Yes, if ur block size is 64mb. Btw, block size is configurable in Hadoop.

Best Regards,
Anil

On Feb 1, 2012, at 5:06 PM, Mark Kerzner <mark.kerzner@shmsoft.com> wrote:

> Anil,
>=20
> do you mean one block of HDFS, like 64MB?
>=20
> Mark
>=20
> On Wed, Feb 1, 2012 at 7:03 PM, Anil Gupta <anilgupta84@gmail.com> wrote:
>=20
>> Do u have enough data to start more than one mapper?
>> If entire data is less than a block size then only 1 mapper will run.
>>=20
>> Best Regards,
>> Anil
>>=20
>> On Feb 1, 2012, at 4:21 PM, Mark Kerzner <mark.kerzner@shmsoft.com> wrote=
:
>>=20
>>> Hi,
>>>=20
>>> I have a simple MR job, and I want each Mapper to get one line from my
>>> input file (which contains further instructions for lengthy processing).=

>>> Each line is 100 characters long, and I tell Hadoop to read only 100
>> bytes,
>>>=20
>>>=20
>> job.getConfiguration().setInt("mapreduce.input.linerecordreader.line.maxl=
ength",
>>> 100);
>>>=20
>>> I see that this part works - it reads only one line at a time, and if I
>>> change this parameter, it listens.
>>>=20
>>> However, on a cluster only one node receives all the map tasks. Only one=

>>> map tasks is started. The others never get anything, they just wait. I'v=
e
>>> added 100 seconds wait to the mapper - no change!
>>>=20
>>> Any advice?
>>>=20
>>> Thank you. Sincerely,
>>> Mark
>>=20