Return-Path: X-Original-To: apmail-hadoop-hdfs-user-archive@minotaur.apache.org Delivered-To: apmail-hadoop-hdfs-user-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id A412BD7BD for ; Wed, 13 Mar 2013 10:15:55 +0000 (UTC) Received: (qmail 75542 invoked by uid 500); 13 Mar 2013 10:15:50 -0000 Delivered-To: apmail-hadoop-hdfs-user-archive@hadoop.apache.org Received: (qmail 75153 invoked by uid 500); 13 Mar 2013 10:15:48 -0000 Mailing-List: contact user-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@hadoop.apache.org Delivered-To: mailing list user@hadoop.apache.org Received: (qmail 75125 invoked by uid 99); 13 Mar 2013 10:15:47 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 13 Mar 2013 10:15:47 +0000 X-ASF-Spam-Status: No, hits=1.5 required=5.0 tests=HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of paul.m.wilkinson@gmail.com designates 209.85.219.47 as permitted sender) Received: from [209.85.219.47] (HELO mail-oa0-f47.google.com) (209.85.219.47) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 13 Mar 2013 10:15:42 +0000 Received: by mail-oa0-f47.google.com with SMTP id o17so871468oag.6 for ; Wed, 13 Mar 2013 03:15:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=vpqb6h37gqorQICwNvkVRM43MJkn7BT9tQMGdosqoD8=; b=X7vtLRKvSoL53nzMrFlov/fe4enb+13i7h4jku61YV1XaT9+epm/LTuUGTmS/TFPhx YsOJ+5lTXTZY0YA2LVSAOu7kvo0fQGgjLQgj3fhWe16FWdpzWlkS8rd7clkEMux9upFX Uv3p5NyuHTyRJ0Ntru1cbWocC8xK3EewN31M3ldShcH6xU6OsN/NrOxA5FKEEb+cVfpM uI51ngdfW1BKGmWv3gvZLjz66sqIISz544G/G1H18Df07Z8kHhw0HO7ZUSujbtlr/OWN wdRQcWqIF9icE+OQuEZGW9aCUMD5Scbl3GFHUoNBYKbk1lryeZbuAZlGIrulbXH7ru7G IM/Q== MIME-Version: 1.0 X-Received: by 10.60.1.225 with SMTP id 1mr14684861oep.141.1363169721595; Wed, 13 Mar 2013 03:15:21 -0700 (PDT) Received: by 10.182.21.135 with HTTP; Wed, 13 Mar 2013 03:15:21 -0700 (PDT) In-Reply-To: References: Date: Wed, 13 Mar 2013 10:15:21 +0000 Message-ID: Subject: Re: Keeping track of the mappers that feed a reducer From: Paul Wilkinson To: user@hadoop.apache.org Content-Type: multipart/alternative; boundary=e89a8fb1fbba068e1904d7cbaf9a X-Virus-Checked: Checked by ClamAV on apache.org --e89a8fb1fbba068e1904d7cbaf9a Content-Type: text/plain; charset=ISO-8859-1 Why not just materialise the mapper information into the values that are emitted? No need to rewrite Hadoop - just change the application code. On 13 March 2013 08:31, preethi ganeshan wrote: > Hi, > I have to modify the Task.java class and the MapTask.java class to keep > track of the mappers that feed a reducer .How do i go about doing this ? > > Regards, > Preethi > --e89a8fb1fbba068e1904d7cbaf9a Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Why not just materialise the mapper information into the values that are em= itted?

No need to rewrite Hadoop - just change the appli= cation code.

On 13 March 2013 08:31, pree= thi ganeshan <preethiganeshan92@gmail.com> wrote:<= br>

Hi,
I have to modify the Task.java class = and the MapTask.java class to keep track of the mappers that feed a reducer= .How do i go about doing this ?

Regards,
Preethi

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