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 3856D9666 for ; Sun, 7 Oct 2012 13:04:08 +0000 (UTC) Received: (qmail 20508 invoked by uid 500); 7 Oct 2012 13:04:07 -0000 Delivered-To: apmail-hadoop-mapreduce-issues-archive@hadoop.apache.org Received: (qmail 20411 invoked by uid 500); 7 Oct 2012 13:04:07 -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 20329 invoked by uid 99); 7 Oct 2012 13:04:06 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Sun, 07 Oct 2012 13:04:06 +0000 Date: Sun, 7 Oct 2012 13:04:05 +0000 (UTC) From: "Harsh J (JIRA)" To: mapreduce-issues@hadoop.apache.org Message-ID: <641495898.6470.1349615046052.JavaMail.jiratomcat@arcas> Subject: [jira] [Updated] (MAPREDUCE-1347) Missing synchronization in MultipleOutputFormat 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-1347?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Harsh J updated MAPREDUCE-1347: ------------------------------- Component/s: client > Missing synchronization in MultipleOutputFormat > ----------------------------------------------- > > Key: MAPREDUCE-1347 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-1347 > Project: Hadoop Map/Reduce > Issue Type: Bug > Components: client > Affects Versions: 1.0.0 > Reporter: Todd Lipcon > Assignee: Harsh J > Attachments: MAPREDUCE-1347.r10.diff, mapreduce.1347.r1.diff, MAPREDUCE-1347.r2.diff, MAPREDUCE-1347.r3.diff, MAPREDUCE-1347.r4.diff, MAPREDUCE-1347.r5.diff, MAPREDUCE-1347.r6.diff, MAPREDUCE-1347.r7.diff, MAPREDUCE-1347.r8.diff, MAPREDUCE-1347.r9.diff > > > MultipleOutputFormat's RecordWriter implementation doesn't use synchronization when accessing the recordWriters member. When using multithreaded mappers or reducers, this can result in problems where two threads will both try to create the same file, causing AlreadyBeingCreatedException. Doing this more fine-grained than just synchronizing the whole method is probably a good idea, so that multithreaded mappers can actually achieve parallelism writing into separate output streams. > From what I can tell, the new API's MultipleOutputs seems not to have this issue. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira