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 ECF8918E20 for ; Thu, 28 May 2015 00:07:19 +0000 (UTC) Received: (qmail 82629 invoked by uid 500); 28 May 2015 00:07:19 -0000 Delivered-To: apmail-hadoop-mapreduce-issues-archive@hadoop.apache.org Received: (qmail 82562 invoked by uid 500); 28 May 2015 00:07:19 -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 82550 invoked by uid 99); 28 May 2015 00:07:19 -0000 Received: from arcas.apache.org (HELO arcas.apache.org) (140.211.11.28) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 28 May 2015 00:07:19 +0000 Date: Thu, 28 May 2015 00:07:19 +0000 (UTC) From: "Guozhang Wang (JIRA)" To: mapreduce-issues@hadoop.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Commented] (MAPREDUCE-1700) User supplied dependencies may conflict with MapReduce system JARs 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-1700?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14562034#comment-14562034 ] Guozhang Wang commented on MAPREDUCE-1700: ------------------------------------------ More specifically, I feel for it to really work, one has to do sth. like: {code} Thread thread = Thread.currentThread(); ClassLoader old = thread.getContextClassLoader(); thread.setContextClassLoader(newClassLoader); try { // user code like process(), map(), reduce(), etc.. } finally { thread.setContextClassLoader(old); } {code} > User supplied dependencies may conflict with MapReduce system JARs > ------------------------------------------------------------------ > > Key: MAPREDUCE-1700 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-1700 > Project: Hadoop Map/Reduce > Issue Type: Bug > Components: task > Reporter: Tom White > Assignee: Tom White > Fix For: 2.0.3-alpha > > Attachments: MAPREDUCE-1700-ccl.patch, MAPREDUCE-1700-ccl.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch > > > If user code has a dependency on a version of a JAR that is different to the one that happens to be used by Hadoop, then it may not work correctly. This happened with user code using a different version of Avro, as reported [here|https://issues.apache.org/jira/browse/AVRO-493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12852081#action_12852081]. > The problem is analogous to the one that application servers have with WAR loading. Using a specialized classloader in the Child JVM is probably the way to solve this. -- This message was sent by Atlassian JIRA (v6.3.4#6332)