Task attempt stopped shuffling and hung the job
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Key: HADOOP-5758
URL: https://issues.apache.org/jira/browse/HADOOP-5758
Project: Hadoop Core
Issue Type: Bug
Affects Versions: 0.18.3
Reporter: Nathan Marz
I was running a job and one of the reducer task attempts got stuck during the
shuffle phase. The percentage complete froze at 33.1%, and the logs for the
attempt looked like:
2009-04-29 15:21:24,431 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0: Got 0 new map-outputs & number of known
map outputs is 0
2009-04-29 15:21:24,431 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0 Scheduled 0 of 0 known outputs (0 slow
hosts and 0 dup hosts)
2009-04-29 15:22:24,580 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0 Need another 1 map output(s) where 0 is
already in progress
2009-04-29 15:22:24,581 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0: Got 0 new map-outputs & number of known
map outputs is 0
2009-04-29 15:22:24,581 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0 Scheduled 0 of 0 known outputs (0 slow
hosts and 0 dup hosts)
2009-04-29 15:23:24,692 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0 Need another 1 map output(s) where 0 is
already in progress
2009-04-29 15:23:24,693 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0: Got 0 new map-outputs & number of known
map outputs is 0
2009-04-29 15:23:24,693 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0 Scheduled 0 of 0 known outputs (0 slow
hosts and 0 dup hosts)
2009-04-29 15:24:24,718 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0 Need another 1 map output(s) where 0 is
already in progress
2009-04-29 15:24:24,718 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0: Got 0 new map-outputs & number of known
map outputs is 0
2009-04-29 15:24:24,719 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0 Scheduled 0 of 0 known outputs (0 slow
hosts and 0 dup hosts)
2009-04-29 15:25:24,742 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0 Need another 1 map output(s) where 0 is
already in progress
2009-04-29 15:25:24,743 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0: Got 0 new map-outputs & number of known
map outputs is 0
2009-04-29 15:25:24,743 INFO org.apache.hadoop.mapred.ReduceTask:
attempt_200904250602_2468_r_000024_0 Scheduled 0 of 0 known outputs (0 slow
hosts and 0 dup hosts)
The mappers and other reducers were long finished. When I manually killed the
task attempt process after 20 minutes of seeing it frozen, it restarted on
another machine and succeeded just fine.
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