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https://issues.apache.org/jira/browse/HADOOP-3155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12616370#action_12616370
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Andreas Kostyrka commented on HADOOP-3155:
------------------------------------------
I'm also getting this behaviour with 0.17.1, on an EC2 hosted cluster, 14
worker (m1.small) and 1 control (NameNode/JobTracker) VMs.
The job was rather small (40 map tasks, with minimal data to each, they fetch
their input internally from S3), 20 reducers. streaming.jar.
As far as I have been able to notice:
-) no progress on reducers (I had cases where jobs have been hanging for
multiples of 12 hours)
-) the configuration is exactly the same on all nodes, so the DFS name idea
from the previous comment does not apply.
-) killing the reduce tasks restarts them on the same node. There they go to
the same state (with the same number of needed outputs) very quickly, the job
being not that big. Then they hang at the same place.
-) the only remedy that I have found if one call this so is restarting the
cluster. So this hang is not 100% input dependant.
Andreas
> reducers stuck at shuffling
> ----------------------------
>
> Key: HADOOP-3155
> URL: https://issues.apache.org/jira/browse/HADOOP-3155
> Project: Hadoop Core
> Issue Type: Bug
> Reporter: Runping Qi
>
> This happened with hadoop-0.16.2:
> In relatively small job (a few hundreds of mappers and reducers), reducers
> were stuck at shuffling.
> I saw the lines like the following repeated hundreds of thousands of times
> over a few hours:
> 2008-04-02 17:17:44,640 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:17:44,641 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:17:44,641 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:17:44,641 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:17:46,643 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:17:46,643 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:17:46,643 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:17:46,643 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:17:48,645 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:17:48,645 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:17:48,645 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:17:48,645 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:17:50,647 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:17:50,647 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:17:50,647 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:17:50,647 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:17:52,649 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:17:52,650 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:17:52,650 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:17:52,650 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:17:54,651 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:17:54,652 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:17:54,652 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:17:54,652 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:17:56,654 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:17:56,654 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:17:56,654 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:17:56,654 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:17:58,656 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:17:58,656 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:17:58,656 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:17:58,656 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:00,658 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:00,658 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:00,658 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:00,658 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:02,660 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:02,661 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:02,661 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:02,661 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:04,662 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:04,663 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:04,663 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:04,663 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:06,664 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:06,665 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:06,665 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:06,665 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:08,667 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:08,667 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:08,667 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:08,667 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:10,669 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:10,669 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:10,669 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:10,669 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:12,671 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:12,671 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:12,671 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:12,671 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:14,673 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:14,674 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:14,674 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:14,674 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:16,675 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:16,676 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:16,676 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:16,676 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:18,678 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:18,678 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:18,678 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:18,678 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:20,680 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:20,680 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:20,680 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
> 2008-04-02 17:18:20,680 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Scheduled 0 of 0 known outputs (0 slow
> hosts and 0 dup hosts)
> 2008-04-02 17:18:22,682 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Need 2 map output(s)
> 2008-04-02 17:18:22,682 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-04-02 17:18:22,682 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804021200_0337_r_000008_0 Got 0 known map output location(s);
> scheduling...
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