MapReduce job is hung after 1 of 5 reducers completed on single-node environment

Posted by Marboni on Server Fault See other posts from Server Fault or by Marboni
Published on 2012-11-09T17:21:44Z Indexed on 2012/11/10 11:06 UTC
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mapreduce

I have only one Data Node on my dev environment on EC2. I ran heavy MR job and in 6 hours noticed that 100% of mappers and 20% of reducers finished (1 of reducer shows 100% competition, other ones - 0%). Looks like job is hung between 2 reducer runs. I don't see any errors in log files.

What it can be?

P.S. Last logs of successfully finished reducer:

2012-11-09 11:29:21,576 INFO org.apache.hadoop.mapred.Task: Task:attempt_201211090523_0004_r_000000_0 is done. And is in the process of commiting
2012-11-09 11:29:22,692 INFO org.apache.hadoop.mapred.Task: Task attempt_201211090523_0004_r_000000_0 is allowed to commit now
2012-11-09 11:29:22,719 INFO org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter: Saved output of task 'attempt_201211090523_0004_r_000000_0' to /data/output/1352457275873/20121109-053433-common
2012-11-09 11:29:22,721 INFO org.apache.hadoop.mapred.Task: Task 'attempt_201211090523_0004_r_000000_0' done.
2012-11-09 11:29:22,725 INFO org.apache.hadoop.mapred.TaskLogsTruncater: Initializing logs' truncater with mapRetainSize=-1 and reduceRetainSize=-1

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