[ http://issues.apache.org/jira/browse/HADOOP-645?page=comments#action_12445029 ] dhruba borthakur commented on HADOOP-645: -----------------------------------------
Not sure if it's just mis-stated, but -reducer NONE doesn't imply no output by reducer, it implies that the mapper itself writes out its output as a dfs file, and the reducer is never even launched. It save transfer of data over the network, sorting by the reducer etc. -Yoram > Map-reduce task does not finish correctly when -reducer NONE is specified > ------------------------------------------------------------------------- > > Key: HADOOP-645 > URL: http://issues.apache.org/jira/browse/HADOOP-645 > Project: Hadoop > Issue Type: Bug > Components: contrib/streaming > Affects Versions: 0.7.2 > Reporter: dhruba borthakur > Assigned To: dhruba borthakur > > Map-reduce task does not finish correctly when -reducer NONE is specified, > The NONE option means that the reducer should not be generating any output. > Using this option causes an exception in the task tracker: > java.lang.IllegalArgumentException: URI is not hierarchical > TaskRunner: at java.io.File.<init>(File.java:335) > TaskRunner: at > org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:583) > TaskRunner: at > org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:96) > TaskRunner: at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:49) > TaskRunner: at org.apache.hadoop.mapred.MapTask.run(MapTask.java:213) > TaskRunner: at > org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:1240) > TaskRunner: sideEffectURI_ file:output length 11 -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
