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Hadoop, mail # user - Map Reduce jobs taking a long time at the end


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Re: Map Reduce jobs taking a long time at the end
ac@...) 2012-12-04, 13:59
Hi,

Have you also checked .out file of the tasktracker in logs? It could contain some useful information for the issue.

Thanks
ac
On 4 Dec 2012, at 8:27 PM, Jay Whittaker wrote:

> Hey,
>
> We are running Map reduce jobs against a 12 machine hbase cluster and
> for a long time they took approx 30 mins to return a result against ~95
> million rows. Without any major changes to the data or any upgrade of
> hbase/hadoop they now seem to be taking about 4 hours. and the logs are
> full of
>
> 2012-12-04 13:33:15,602 INFO org.apache.hadoop.mapred.TaskTracker:
> attempt_201211210952_0293_m_000031_0 0.0% row: 63 6f 6d 2e 70 72 6f 75
> 67 68 74
> ...
> 2012-12-04 13:45:17,134 INFO org.apache.hadoop.mapred.TaskTracker:
> attempt_201211210952_0293_m_000031_0 0.0% row: 63 6f 6d 2e 70 75 72 70
> 6c 65 64 65 73 69 67 6e 73 65 72 76 69 63 65 73
> ...
> 2012-12-04 13:46:11,515 INFO org.apache.hadoop.mapred.TaskTracker:
> attempt_201211210952_0293_m_000031_0 0.0% row: 63 6f 6d 2e 70 75 73 68
> 74 6f 74 61 6c 6b 2d 6f 6e 6c 69 6e 65
>
> I presume the 0% is percent complete but I'm not sure as to why the time
> to complete has now jumped massively. Ganglia shows no major load on the
> nodes in question so I don't think it's that.
>
> What steps should I be taking to try troubleshoot the problem?
>
> Regards,
>
> Jay