Return-Path: X-Original-To: apmail-hadoop-mapreduce-issues-archive@minotaur.apache.org Delivered-To: apmail-hadoop-mapreduce-issues-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 53DA6105FF for ; Fri, 6 Dec 2013 16:51:47 +0000 (UTC) Received: (qmail 78914 invoked by uid 500); 6 Dec 2013 16:51:42 -0000 Delivered-To: apmail-hadoop-mapreduce-issues-archive@hadoop.apache.org Received: (qmail 78729 invoked by uid 500); 6 Dec 2013 16:51:40 -0000 Mailing-List: contact mapreduce-issues-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: mapreduce-issues@hadoop.apache.org Delivered-To: mailing list mapreduce-issues@hadoop.apache.org Received: (qmail 78701 invoked by uid 99); 6 Dec 2013 16:51:38 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 06 Dec 2013 16:51:38 +0000 Date: Fri, 6 Dec 2013 16:51:38 +0000 (UTC) From: "Milind Bhandarkar (JIRA)" To: mapreduce-issues@hadoop.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Commented] (MAPREDUCE-5649) Reduce cannot use more than 2G memory for the final merge MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-JIRA-FingerPrint: 30527f35849b9dde25b450d4833f0394 [ https://issues.apache.org/jira/browse/MAPREDUCE-5649?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13841409#comment-13841409 ] Milind Bhandarkar commented on MAPREDUCE-5649: ---------------------------------------------- Folks, is there any reason behind limiting this amount of memory to 2GB ? > Reduce cannot use more than 2G memory for the final merge > ---------------------------------------------------------- > > Key: MAPREDUCE-5649 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-5649 > Project: Hadoop Map/Reduce > Issue Type: Bug > Components: mrv2 > Affects Versions: trunk > Reporter: stanley shi > > In the org.apache.hadoop.mapreduce.task.reduce.MergeManagerImpl.java file, in the finalMerge method: > int maxInMemReduce = (int)Math.min( > Runtime.getRuntime().maxMemory() * maxRedPer, Integer.MAX_VALUE); > > This means no matter how much memory user has, reducer will not retain more than 2G data in memory before the reduce phase starts. -- This message was sent by Atlassian JIRA (v6.1#6144)