Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-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 6B478FF17 for ; Fri, 29 Mar 2013 14:29:33 +0000 (UTC) Received: (qmail 59112 invoked by uid 500); 29 Mar 2013 14:29:31 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 58550 invoked by uid 500); 29 Mar 2013 14:29:25 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 58510 invoked by uid 99); 29 Mar 2013 14:29:24 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 29 Mar 2013 14:29:24 +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 jbellis@gmail.com designates 209.85.217.174 as permitted sender) Received: from [209.85.217.174] (HELO mail-lb0-f174.google.com) (209.85.217.174) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 29 Mar 2013 14:29:20 +0000 Received: by mail-lb0-f174.google.com with SMTP id s10so367490lbi.33 for ; Fri, 29 Mar 2013 07:28:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:mime-version:in-reply-to:references:from:date:message-id :subject:to:content-type; bh=aZ77YmfXCPeExB+RPas+v38TzYCq8RB15e7p6qgEQhg=; b=N41U2hKnjuLVHYE+uDMuDQ3Py2YXB+k8XP3tsYUdXWqeeTmC9fhZ06Qo/p2HF9qddp 7NDBDelP8Y8jI6E8mRG1bSoCoxiwovtWuI/TUaLOmqBFEgWHw9Mc/s52A+sUa+8SBEVm kU3/FZJpMRvC5DHx12hHf2P0QKWT1L5gglWKEE4PWxNd8dGO4ziF9auyUon0VlPg8dKh NrJc+N/CpOsjU7sDDGTJowfXi494GsTgiXC5yy6UVqqKrc1CLY4FUckV/GnVJB1h0JCX zX8ef+TzgBvyTrbDe9BVYsEPjJImgl8Vmhypkt0AtFl7zUKqIzUx9LszepYitC0BGugn RmFw== X-Received: by 10.152.122.100 with SMTP id lr4mr1276963lab.28.1364567338319; Fri, 29 Mar 2013 07:28:58 -0700 (PDT) MIME-Version: 1.0 Received: by 10.112.38.101 with HTTP; Fri, 29 Mar 2013 07:28:38 -0700 (PDT) In-Reply-To: References: From: Jonathan Ellis Date: Fri, 29 Mar 2013 09:28:38 -0500 Message-ID: Subject: Re: Vnodes - HUNDRED of MapReduce jobs To: user@cassandra.apache.org Content-Type: text/plain; charset=ISO-8859-1 X-Virus-Checked: Checked by ClamAV on apache.org I still don't see the hole in the following reasoning: - Input splits are 64k by default. At this size, map processing time dominates job creation. - Therefore, if job creation time dominates, you have a toy data set (< 64K * 256 vnodes = 16 MB) Adding complexity to our inputformat to improve performance for this niche does not sound like a good idea to me. On Thu, Mar 28, 2013 at 8:40 AM, cem wrote: > Hi Alicia , > > Cassandra input format creates mappers as many as vnodes. It is a known > issue. You need to lower the number of vnodes :( > > I have a simple solution for that and ready to write a patch. Should I > create a ticket about that? I don't know the procedure about that. > > Regards, > Cem > > > On Thu, Mar 28, 2013 at 2:30 PM, Alicia Leong wrote: >> >> Hi All, >> >> I have 3 nodes of Cassandra 1.2.3 & edited the cassandra.yaml for vnodes. >> >> When I execute a M/R job .. the console showed HUNDRED of Map tasks. >> >> May I know, is the normal since is vnodes? If yes, this have slow the M/R >> job to finish/complete. >> >> >> Thanks > > -- Jonathan Ellis Project Chair, Apache Cassandra co-founder, http://www.datastax.com @spyced