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From "Mike Smith" <mike.smith....@gmail.com>
Subject Re: some reducers stock in copying stage
Date Wed, 28 Feb 2007 18:04:20 GMT
Thanks Devaraj, patch 1042 seems to be already committed. Also, the system
never recovered even after 1 min, 300 sec, it stocked there for hours. I
will try patch 1043 and also decrease the back-off time to see if those help

Mike


On 2/27/07, Devaraj Das <ddas@yahoo-inc.com> wrote:
>
> Mike,
> The patches for h-1042 and h-1043 should address your situation better.
> They
> have not been committed as yet. Please apply the patches manually and see
> whether the situation improves.
> Thanks,
> Devaraj.
>
> > -----Original Message-----
> > From: Devaraj Das [mailto:ddas@yahoo-inc.com]
> > Sent: Wednesday, February 28, 2007 11:54 AM
> > To: 'hadoop-dev@lucene.apache.org'
> > Subject: RE: some reducers stock in copying stage
> >
> > Looks like all hosts (from which map outputs haven't yet been fetched)
> are
> > classified as being "slow". That is because there were failures earlier
> > while fetching outputs from those. When failures happen (maybe due to
> > insufficient jetty server threads), there is a back-off for that host
> and
> > until the time in the back-off expires the outputs won't be fetched from
> > that particular host. The system should recover from this though.
> Another
> > thing you might want to try is to reduce the value of the
> > mapred.reduce.copy.backoff to a value like 5 (the number of seconds, by
> > default it is 300 seconds). This will ensure that the back-off is always
> > less than or equal to 1 min,5 secs (1 min is the minimum hardcoded
> > backoff).
> >
> > > -----Original Message-----
> > > From: Mike Smith [mailto:mike.smith.dev@gmail.com]
> > > Sent: Wednesday, February 28, 2007 8:45 AM
> > > To: hadoop-dev@lucene.apache.org
> > > Subject: some reducers stock in copying stage
> > >
> > > After updating the hadoop trunk today, I am having problem at the
> > reducing
> > > phase. Some of the reducers stock in the copying stage (very end of
> > > copying)
> > > and they keep reporting the same status, even when I kill the related
> > > tasktracker, the job traker still reports the copying. Here is the
> log:
> > >
> > > 2007-02-27 22:08:26,388 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Got 24 known map output location(s);
> scheduling...
> > > 2007-02-27 22:08:26,388 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Scheduled 0 of 24 known outputs (24 slow hosts
> and
> > 0
> > > dup hosts)
> > > 2007-02-27 22:08:27,204 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:27,204 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:28,214 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:28,214 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:29,224 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:29,224 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:30,114 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Need 11 map output(s)
> > > 2007-02-27 22:08:30,114 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Need 234 map output location(s)
> > > 2007-02-27 22:08:30,116 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Got 0 new map outputs from jobtracker and 0 map
> > > outputs
> > > from previous failures
> > > 2007-02-27 22:08:30,116 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Got 11 known map output location(s);
> scheduling...
> > > 2007-02-27 22:08:30,116 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Scheduled 0 of 11 known outputs (11 slow hosts
> and
> > 0
> > > dup hosts)
> > > 2007-02-27 22:08:30,234 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:30,234 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:31,244 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:31,244 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:31,394 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Need 24 map output(s)
> > > 2007-02-27 22:08:31,394 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Need 133 map output location(s)
> > > 2007-02-27 22:08:31,395 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Got 0 new map outputs from jobtracker and 0 map
> > > outputs
> > > from previous failures
> > > 2007-02-27 22:08:31,395 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Got 24 known map output location(s);
> scheduling...
> > > 2007-02-27 22:08:31,395 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Scheduled 0 of 24 known outputs (24 slow hosts
> and
> > 0
> > > dup hosts)
> > > 2007-02-27 22:08:32,254 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:32,254 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:33,264 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:33,264 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:34,274 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:34,274 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:35,124 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Need 11 map output(s)
> > > 2007-02-27 22:08:35,124 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Need 234 map output location(s)
> > > 2007-02-27 22:08:35,219 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Got 0 new map outputs from jobtracker and 0 map
> > > outputs
> > > from previous failures
> > > 2007-02-27 22:08:35,219 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Got 11 known map output location(s);
> scheduling...
> > > 2007-02-27 22:08:35,219 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000111_0 Scheduled 0 of 11 known outputs (11 slow hosts
> and
> > 0
> > > dup hosts)
> > > 2007-02-27 22:08:35,284 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:35,284 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:36,294 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000224_0 0.33083335% reduce > copy (3176 of 3200 at 1.94
> > MB/s)
> > > >
> > > 2007-02-27 22:08:36,294 INFO org.apache.hadoop.mapred.TaskTracker:
> > > task_0001_r_000111_0 0.3321875% reduce > copy (3189 of 3200 at 0.40
> > MB/s)
> > > >
> > > 2007-02-27 22:08:36,404 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Need 24 map output(s)
> > > 2007-02-27 22:08:36,404 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Need 133 map output location(s)
> > > 2007-02-27 22:08:36,422 INFO org.apache.hadoop.mapred.TaskRunner:
> > > task_0001_r_000224_0 Got 0 new map outputs from jobtracker and 0 map
> > > outputs
> > > from previous
>
>

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