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From skaterQiang <xqfly...@163.com>
Subject How to debug map reduce in distributed model
Date Wed, 29 Jun 2011 12:39:35 GMT
Hello guys:
        I want to debug the map reduce tasks, especially org.apache.hadoop.mapred.ReduceTask
I want to understand how the data flow work.
So I add the following in the mapred-site.xml
<property>
        <name>mapred.child.java.opts</name>
        <value>-Xdebug -Xrunjdwp:transport=dt_socket,address=8888,server=y,suspend=y</value>
    </property>
mapreduce.tasktracker.map.tasks.maximum 1
mapreduce.tasktracker.reduce.tasks.maximum 1
But by debugging JvmRunner, the -Xdebug is not added into the JVM start up command.
Why? Is there some where guard this?
Or I have to build hadoop with my debug code?


Regards,
Skater


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