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https://issues.apache.org/jira/browse/HADOOP-3332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12595786#action_12595786
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Runping Qi commented on HADOOP-3332:
------------------------------------
The patch looks good.
It should be checked into 17 too.
Without this fix, the log file of EACH reduce task can easily reach gig bytes
in size; any useful information
will be burried in the huge volume of repeated noise, thus will be hard to
find. Log archiving will also be problematic.
> improving the logging during shuffling
> --------------------------------------
>
> Key: HADOOP-3332
> URL: https://issues.apache.org/jira/browse/HADOOP-3332
> Project: Hadoop Core
> Issue Type: Improvement
> Components: mapred
> Reporter: Runping Qi
> Assignee: Devaraj Das
> Priority: Critical
> Fix For: 0.18.0
>
> Attachments: 3332.branch17.patch, 3332.patch, 3332.patch
>
>
> Below is an excerpt from the log file of a reducer.
> A same set of of messages about fetching schedule is logged every second.
> Yet, the critical information --- which hosts were slow --- was not there.
>
> 2008-05-01 00:33:13,215 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0 Need another 3 map output(s) where 1 is
> already in progress
> 2008-05-01 00:33:14,216 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-05-01 00:33:14,216 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0 Got 2 known map output location(s);
> scheduling...
> 2008-05-01 00:33:14,216 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0 Scheduled 0 of 2 known outputs (2 slow
> hosts and 0 dup hosts)
> 2008-05-01 00:33:14,216 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0 Need another 3 map output(s) where 1 is
> already in progress
> 2008-05-01 00:33:15,217 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
> 2008-05-01 00:33:15,217 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0 Got 2 known map output location(s);
> scheduling...
> 2008-05-01 00:33:15,217 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0 Scheduled 0 of 2 known outputs (2 slow
> hosts and 0 dup hosts)
> 2008-05-01 00:33:15,217 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0 Need another 3 map output(s) where 1 is
> already in progress
> 2008-05-01 00:33:16,218 INFO org.apache.hadoop.mapred.ReduceTask:
> task_200804302255_0002_r_000720_0: Got 0 new map-outputs & 0 obsolete
> map-outputs from tasktracker and 0 map-outputs from previous failures
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