Mailing-List: contact user-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: user@hadoop.apache.org
Received-SPF: pass (nike.apache.org: domain of vinodkv@hortonworks.com
 designates 209.85.220.47 as permitted sender)
From: Vinod Kumar Vavilapalli <vinodkv@hortonworks.com>
Mime-Version: 1.0 (Apple Message framework v1283)
Content-Type: multipart/alternative;
 boundary="Apple-Mail=_7DA23415-C37F-4115-A9C5-4EF73383EEAC"
Subject: Re: Selecting a task for the tasktracker
Date: Thu, 27 Dec 2012 10:11:14 -0800
In-Reply-To: 
 <CAEAKFL-f2y_ZkyfgCOTTTFwXO6yst642kU3FVRN2xDd2UoaQHQ@mail.gmail.com>
To: user@hadoop.apache.org
References: 
 <CAKj4OnzTxytii4ZY38fS_sqRmi19ajc=0ps1OvvZCYNJwZa+MA@mail.gmail.com>
 <CAEAKFL-f2y_ZkyfgCOTTTFwXO6yst642kU3FVRN2xDd2UoaQHQ@mail.gmail.com>
Message-Id: <B28E569F-B4B3-4F67-B8CB-7CB9386013DA@apache.org>


--Apple-Mail=_7DA23415-C37F-4115-A9C5-4EF73383EEAC
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=iso-8859-1


On top of that, the message indicates that you need to have your =
scheduler class in the mapred package.

Thanks,
+Vinod Kumar Vavilapalli
Hortonworks Inc.
http://hortonworks.com/

On Dec 27, 2012, at 7:38 AM, Hemanth Yamijala wrote:

> Hi,
>=20
> Firstly, I am talking about Hadoop 1.0. Please note that in Hadoop 2.x =
and trunk, the Mapreduce framework is completely revamped to Yarn =
(http://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/YARN.h=
tml) and you may need to look at different interfaces for building your =
own scheduler.
>=20
> In 1.0, the primary function of the TaskScheduler is the assignTasks =
method. Given a TaskTracker object as input, this method figures out how =
many free map and reduce slots exist in that particular tasktracker and =
selects one or more task that can be scheduled on it. Since task =
selection is the primary responsibility and the granularity is at a task =
level, the class is called TaskScheduler.
>=20
> The method of choosing a job and then a task within the job is =
customised by the different schedulers already present in Hadoop. Also, =
the core logic of selecting a map task with data locality optimizations =
is not implemented in the schedulers per se, but they rely on the =
JobInProgress object in MapReduce framework for achieving the same.
>=20
> To implement your own Scheduler, it may be best to look at the sources =
of existing schedulers: JobQueueTaskScheduler, CapacityTaskScheduler or =
FairScheduler.  In particular, the last two are in the contrib modules =
of mapreduce, and hence will be fairly independent to follow. Their =
build files will also tell you how to resolve any compile problems like =
the one you are facing.
>=20
> Thanks
> Hemanth =20
>=20
>=20
>=20
>=20
> On Thu, Dec 27, 2012 at 4:10 PM, Yaron Gonen <yaron.gonen@gmail.com> =
wrote:
> Hi,
> If I understand correctly, the job scheduler (why is the class called =
TaskScheduler?) is responsible for assigning the task whose split is as =
close as possible to the tasktacker.
> Meaning that the job scheduler is responsible to two things:
> Selecting a job.
> Once a job is selected, assign the closest task to the tasktracker =
that send the heartbeat.
> Is this correct?
>=20
> I want to write my own job scheduler to change the logic above, but it =
says The type TaskScheduler is not visible.
> How can I write my own scheduler?
>=20
> thanks
>=20


--Apple-Mail=_7DA23415-C37F-4115-A9C5-4EF73383EEAC
Content-Transfer-Encoding: 7bit
Content-Type: text/html;
	charset=iso-8859-1

<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br></div><div>On top of that, the message indicates that you need to have your scheduler class in the mapred package.</div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div><div class="">Thanks,</div><div class="">+Vinod Kumar Vavilapalli</div><div class="">Hortonworks Inc.<br class=""><a href="http://hortonworks.com/" class="">http://hortonworks.com/</a></div></div></span>
</div>

<br><div><div>On Dec 27, 2012, at 7:38 AM, Hemanth Yamijala wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hi,<div><br></div><div>Firstly, I am talking about Hadoop 1.0. Please note that in Hadoop 2.x and trunk, the Mapreduce framework is completely revamped to Yarn (<a href="http://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/YARN.html">http://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/YARN.html</a>) and you may need to look at different interfaces for building your own scheduler.</div>
<div><br></div><div>In 1.0, the primary function of the TaskScheduler is the assignTasks method. Given a TaskTracker object as input, this method figures out how many free map and reduce slots exist in that particular tasktracker and selects one or more task that can be scheduled on it. Since task selection is the primary responsibility and the granularity is at a task level, the class is called TaskScheduler.</div>
<div><br></div><div>The method of choosing a job and then a task within the job is customised by the different schedulers already present in Hadoop. Also, the core logic of selecting a map task with data locality optimizations is not implemented in the schedulers per se, but they rely on the JobInProgress object in MapReduce framework for achieving the same.</div>
<div><br></div><div>To implement your own Scheduler, it may be best to look at the sources of existing schedulers: JobQueueTaskScheduler, CapacityTaskScheduler or FairScheduler. &nbsp;In particular, the last two are in the contrib modules of mapreduce, and hence will be fairly independent to follow. Their build files will also tell you how to resolve any compile problems like the one you are facing.</div>
<div><br></div><div>Thanks</div><div>Hemanth &nbsp;</div><div><br></div><div><br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Dec 27, 2012 at 4:10 PM, Yaron Gonen <span dir="ltr">&lt;<a href="mailto:yaron.gonen@gmail.com" target="_blank">yaron.gonen@gmail.com</a>&gt;</span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi,<div>If I understand correctly, the job scheduler (why is the class called TaskScheduler?) is responsible for assigning the task whose split is as close as possible to the tasktacker.</div>
<div>
Meaning that the job scheduler is responsible to two things:</div><div><ol><li>Selecting a job.</li><li>Once a job is selected, assign the closest task to the tasktracker that send the heartbeat.</li>
</ol><div>Is this correct?</div><div><br></div><div>I want to write my own job scheduler to change the logic above, but it says&nbsp;<font face="courier new, monospace">The type TaskScheduler is not visible</font>.</div>
<div>How can I write my own scheduler?</div><div><br></div><div>thanks</div></div></div>
</blockquote></div><br></div>
</blockquote></div><br></body></html>
--Apple-Mail=_7DA23415-C37F-4115-A9C5-4EF73383EEAC--