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MapReduce >> mail # user >> Re: Reduce task hang[EMERGENCE]


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Re: Reduce task hang[EMERGENCE]
Hi Harsh,
Thanks.

There is no any error logs for attempt_201312201200_34795_r_000000_0 in the
tasktracker log. only '0.0% reduce > copy >'

I configured all hosts in all slaves and master.

This job has only one reduce. it hanged. but I configured everybody's max
job running to '1' in the Fair scheduler file.

but some people's max job running greater than one. and these people's job
never hanged...
On Fri, Jan 3, 2014 at 1:13 PM, Harsh J <[EMAIL PROTECTED]> wrote:

> Does the Reduce task log (of attempt_201312201200_34795_r_000000_0)
> show any errors in trying to communicate with the various TaskTrackers
> in trying to obtain the data?
>
> On Fri, Jan 3, 2014 at 9:54 AM, Azuryy Yu <[EMAIL PROTECTED]> wrote:
> > Add addtional:
> >
> > Our MR version is 1.2.1, not 1.0.4
> >
> > There is no useful information in the JT log.
> >
> >
> > On Fri, Jan 3, 2014 at 12:20 PM, Azuryy Yu <[EMAIL PROTECTED]> wrote:
> >>
> >> Hi,
> >>
> >> Our prod cluster met some issues recently,
> >> All map tasks finished successfully, but reduce task hanged.
> >>
> >> but It's not happened on all TaskTrackers, only sometimes. we used
> >> mapred-1.0.4
> >>
> >> There is "0.0% reduce > copy >" forever until kill task manually.
> >>
> >> reduce logs on the TaskTracker:
> >> hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:13:57 INFO
> >> mapred.TaskTracker: JVM with ID: jvm_201312201200_34795_r_-365330778
> given
> >> task: attempt_201312201200_34795_r_000000_0
> >> hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:04 INFO
> >> mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce >
> copy
> >> >
> >> hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:08 INFO
> >> mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce >
> copy
> >> >
> >> hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:14 INFO
> >> mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce >
> copy
> >> >
> >> hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:17 INFO
> >> mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce >
> copy
> >> >
> >> hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:23 INFO
> >> mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce >
> copy
> >> >
> >
> >
>
>
>
> --
> Harsh J
>