[ https://issues.apache.org/jira/browse/MAPREDUCE-5821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13960824#comment-13960824 ]
Hadoop QA commented on MAPREDUCE-5821: -------------------------------------- {color:red}-1 overall{color}. Here are the results of testing the latest attachment http://issues.apache.org/jira/secure/attachment/12638796/mapreduce-5821.txt against trunk revision . {color:green}+1 @author{color}. The patch does not contain any @author tags. {color:red}-1 tests included{color}. The patch doesn't appear to include any new or modified tests. Please justify why no new tests are needed for this patch. Also please list what manual steps were performed to verify this patch. {color:green}+1 javac{color}. The applied patch does not increase the total number of javac compiler warnings. {color:green}+1 javadoc{color}. There were no new javadoc warning messages. {color:green}+1 eclipse:eclipse{color}. The patch built with eclipse:eclipse. {color:green}+1 findbugs{color}. The patch does not introduce any new Findbugs (version 1.3.9) warnings. {color:green}+1 release audit{color}. The applied patch does not increase the total number of release audit warnings. {color:green}+1 core tests{color}. The patch passed unit tests in hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core. {color:green}+1 contrib tests{color}. The patch passed contrib unit tests. Test results: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4487//testReport/ Console output: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4487//console This message is automatically generated. > IFile merge allocates new byte array for every value > ---------------------------------------------------- > > Key: MAPREDUCE-5821 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-5821 > Project: Hadoop Map/Reduce > Issue Type: Bug > Components: performance, task > Affects Versions: 2.4.1 > Reporter: Todd Lipcon > Assignee: Todd Lipcon > Attachments: after-patch.png, before-patch.png, mapreduce-5821.txt, > mapreduce-5821.txt > > > I wrote a standalone benchmark of the MapOutputBuffer and found that it did a > lot of allocations during the merge phase. After looking at an allocation > profile, I found that IFile.Reader.nextRawValue() would always allocate a new > byte array for every value, so the allocation rate goes way up during the > merge phase of the mapper. I imagine this also affects the reducer input, > though I didn't profile that. -- This message was sent by Atlassian JIRA (v6.2#6252)