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From Pedro Costa <psdc1...@gmail.com>
Subject How to debug ReduceTask?
Date Sun, 29 Aug 2010 01:24:18 GMT
Hi, I would like to debug the shuffle phase from a Reducer, but I
can't because the Reducer starts as a new process. I've tried all the
options that some pages says, but it doesn't work in the way that I
want.

I've tried the IsolationRunner class and the LocaJobRunner, but I
couldn't put them to work properly. I've also tried these classes with
the option

<property>
  <name>mapred.job.tracker</name>
  <value>local</value>
</property>

 but the tasktracker won't run, because it says that local is not in
the format of host and port.

I've also tried with a downloaded class called SingleProcessHadoop,
but I also can't debug the Reducer because the Reduce Task runs as a
new process.

Can anyone give me a fully working example that can allow me to put
debug point in the ReduceTask?


Thanks,
-- 
PSC

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