Return-Path: 
 <user-return-19003-apmail-hadoop-common-user-archive=hadoop.apache.org@hadoop.apache.org>
X-Original-To: apmail-hadoop-common-user-archive@www.apache.org
Delivered-To: apmail-hadoop-common-user-archive@www.apache.org
Received: from mail.apache.org (hermes.apache.org [140.211.11.3])
	by minotaur.apache.org (Postfix) with SMTP id 2F03717A3F
	for <apmail-hadoop-common-user-archive@www.apache.org>;
 Mon,  9 Mar 2015 14:57:07 +0000 (UTC)
Received: (qmail 47925 invoked by uid 500); 9 Mar 2015 14:56:55 -0000
Delivered-To: apmail-hadoop-common-user-archive@hadoop.apache.org
Received: (qmail 47810 invoked by uid 500); 9 Mar 2015 14:56:55 -0000
Mailing-List: contact user-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
List-Help: <mailto:user-help@hadoop.apache.org>
List-Unsubscribe: <mailto:user-unsubscribe@hadoop.apache.org>
List-Post: <mailto:user@hadoop.apache.org>
List-Id: <user.hadoop.apache.org>
Reply-To: user@hadoop.apache.org
Delivered-To: mailing list user@hadoop.apache.org
Received: (qmail 47793 invoked by uid 99); 9 Mar 2015 14:56:55 -0000
Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136)
    by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 09 Mar 2015 14:56:55 +0000
X-ASF-Spam-Status: No, hits=-0.7 required=5.0
	tests=RCVD_IN_DNSWL_LOW,SPF_PASS
X-Spam-Check-By: apache.org
Received-SPF: pass (athena.apache.org: domain of xeonmailinglist@gmail.com
 designates 209.85.212.173 as permitted sender)
Received: from [209.85.212.173] (HELO mail-wi0-f173.google.com)
 (209.85.212.173)
    by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 09 Mar 2015 14:56:47 +0000
Received: by widex7 with SMTP id ex7so20782959wid.1
        for <user@hadoop.apache.org>; Mon, 09 Mar 2015 07:56:26 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20120113;
        h=message-id:date:from:user-agent:mime-version:to:subject
         :content-type:content-transfer-encoding;
        bh=A9JrWlJWVb/FrcUZ62ykNyaFzI6iHIuwFML4o032Fdg=;
        b=Y6IChXyKmtapAai5ZypmxI44sZX7OJEiQtC2lAjadHWmYdFIC5ZXPd2rycWjARHqru
         j/RkKurVoaCm0SvEgLSP0BV3oDdcqagBuUTgyZ76g+OvhqNyFK/2lJlSSYFWcMIZsRIy
         +bSCtoznVsE9oC/lvVjpgxLY5IvkRInRA3u3MjmR7AN/ignlpmo3xi7wuKcKqVe043/t
         NVhHKmfCIQ4MYop19wcBTL43iX6BHaYsdTR5pY5Ky/ioaakrOq8wdtCNJz4sN3qnkc3+
         pcU3O8yaDBnjJY+9o2xCOJOj6fgrZDSt2AQXsQw8Fxenk4dxO+ktpGih7uQtCLJiRuW3
         Q2tg==
X-Received: by 10.194.78.114 with SMTP id a18mr59851454wjx.0.1425912986877;
        Mon, 09 Mar 2015 07:56:26 -0700 (PDT)
Received: from [10.101.227.125] ([194.117.18.101])
        by mx.google.com with ESMTPSA id
 g5sm28592854wjr.19.2015.03.09.07.56.25
        for <user@hadoop.apache.org>
        (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Mon, 09 Mar 2015 07:56:25 -0700 (PDT)
Message-ID: <54FDB497.6040009@gmail.com>
Date: Mon, 09 Mar 2015 14:56:23 +0000
From: xeonmailinglist-gmail <xeonmailinglist@gmail.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64;
 rv:31.0) Gecko/20100101 Thunderbird/31.5.0
MIME-Version: 1.0
To: "user@hadoop.apache.org" <user@hadoop.apache.org>
Subject: How reduce tasks know which partition they should read?
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Virus-Checked: Checked by ClamAV on apache.org

Hi,

I am looking to the Yarn mapreduce internals to try to understand how 
reduce tasks know which partition of the map output they should read. 
Even, when they re-execute after a crash?

I am also looking to the mapreduce source code. Is there any class that 
I should look to try to understand this question?

Any help?

Thanks


-- 
--