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Hadoop, mail # user - Reduce task hang[EMERGENCE]


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Re: Reduce task hang[EMERGENCE]
Azuryy Yu 2014-01-03, 04:24
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 >
>