How to print on console during MapReduce job execution in hadoop

开发者_如何学Go

I want to print each step of my "map" after its execution on the console.

Something like

System.out.println("Completed Step one"); System.out.println("Completed Step two");

and so on

Is there a special command to do that or is it not possible at all, as System.out.println doesn't seem to work at all ?

Please guide

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You can use System.out.println(... To see whats been printed, open the jobtracker web console. Then navigate to your submitted job's link. On the Job page, you will see links to all your individual Map/Reduce tasks. Follow the links.. you will find a link that displays the dump of both the Standard output as well as the Standard error.

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You can use the stdout yarn log to check the prints done with System.out.println(). Check this answer:

https://stackoverflow.com/a/35526819/3998212