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https://issues.apache.org/jira/browse/HADOOP-3155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12612949#action_12612949
]
Derek Wollenstein commented on HADOOP-3155:
-------------------------------------------
I noticed something similar occuring to the original issue description (
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))
) repeated over and over again
It seems that this is triggered if different nodes are configured to use a
different dfs name, including the following
on the TaskTracker and JobTracker instances
fs.default.name = "foo.example.com:50001"
on the DataNode instances
fs.default.name = "hdfs://foo.example.com:50001/"
This seems to cause the reducers to be unable to find the mapper output
> 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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