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From David Rosenstrauch <dar...@darose.net>
Subject Re: Three Questions
Date Tue, 03 May 2011 22:08:50 GMT
On 05/03/2011 05:49 PM, Geoffry Roberts wrote:
> David,
> Thanks for the response.
> Last thing first:
> I am using org.apache.hadoop.mapreduce.lib.output.MultipleOutputs
> which is differs from what your link points to
> org.apache.hadoop.mapred.lib.MultipleOutputs. Using the class you propose,
> requires me to use a number of other classes from the same package.  These
> used to be deprecated, but apparently are not any more.
> Question: Does my package even work?  Must I use the other?

My apologies, I sent you the wrong link.  Should be this:


Point remains the same though:  you need to call 
MultipleOutputs.addNamedOutput() to configure the named output before 
you can start writing to it.

> So far as the logging goes, I didn't quite follow your response.  You say
> "You can find an individual map or reduce task's logs here:"  but there is
> no link.
> I am familiar with the drill down that starts by clicking NameNode
> Logs/userlogs/job*/attempt*r*/stdout.  Are you recommending something
> different?

I am.  I wasn't recommending a specific link, but rather for you to 
click on links in one of your own M/R jobs in your Hadoop GUI.  I.e.:

* go to http:<your job tracker>:50030
* click on a job
* click on (e.g.) the word "reduce" in the UI, which brings you to the 
"All Tasks" page

> btw,
> In my Reduce class, I have a System.out statement in the setup() method that
> works (i.e. I get output.), but similar statements in the reduce() method
> yield nada.

System.out.println won't output to the job log like I'm describing 
above.  (Plus you'll have no control over the logging level.)  Using the 
logging framework is much preferred.



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