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From "wangxiaowei" <wangxiao...@software.ict.ac.cn>
Subject I need your help sincerely!
Date Tue, 22 Apr 2008 08:39:14 GMT
hello, I am a Chinese user.I am using hadoop-0.15.3 now.The problem is that:I install hadoop
with three nodes.One is taken as NameNode and JobTracker.The three are all taken as slaves.
It dfs runs normally.I use your example of wordcount,the instruction is:bin/hadoop jar hadoop-0.15.3-examples.jar
wordcount -m 6 -r 2 inputfile outoutdir then I submit it.when it runs,the map tasks are all
completes,but the reduce task do not run at all! I checked the log of JobTracker,finding the
    at java.util.Hashtable.get(Hashtable.java:334)
    at org.apache.hadoop.mapred.ReduceTask$ReduceCopier.fetchOutput(ReduceTask.java:966)
    at org.apache.hadoop.mapred.ReduceTask.run
    at org.apache.hadoop.mapred.TaskTracker$Child.main()
the machine just stoped there,I have to ctrl+c to stop the program.
but when I use this instructon:bin/hadoop jar hadoop-0.15.3-examples.jar wordcount -m 2 -r
1 inputfile outoutdir
   it runs successfully!
   I do not konw why! I think the numbers of machines should be greater than mapTasks,so i
set it 6.my machines number is 3.
   Looking forward for your reply!
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