Hi,
MapReduce framework provide different in built approaches to debug a Job: 1) LocalJobRunner (Running the Job without a cluster; check basic functionality of the Job implementation) 2) IsolationRunner (Running a failed TaskAttempt on cluster- Remote debugging can be done) Apart from this we can use Sysouts and loggings in the Map or Reduce Tasks. These logs will come in "sysout","syslog","syserr" accordingly. These files will be present in the userlogs folder. User can pass Remote Debug argument to Child Process to enable remote debugging of Child process. If you have access through putty, then you can use remote Debug option and connect through eclipse as well. Regards, Subroto Sanyal _____ From: bejoy.had...@gmail.com [mailto:bejoy.had...@gmail.com] Sent: Thursday, September 15, 2011 9:49 AM To: mapreduce-user@hadoop.apache.org Subject: Re: Debugging Mapreduce programs Shreya There are multiple ways to debug map reduce programs. I found comfortable using the jobtracker web UI. You can your job tracker web UI at http://<server ip>:50030/jobtracker.jsp Open it in a browser. There you can find the running,failed and retired jobs. You can drill down on any job to task tracker log levels from there. Mostly I get the root cause of my job failures from there. Hope it helps Regards Bejoy K S _____ From: <shreya....@cognizant.com> Date: Thu, 15 Sep 2011 09:39:23 +0530 To: <mapreduce-user@hadoop.apache.org> ReplyTo: mapreduce-user@hadoop.apache.org Subject: Debugging Mapreduce programs Hi Can we use sysouts in java to debug MR programs. Where would those sysouts be printed? What would be the best way to debug a remote system where I have access to the machine only through putty. Regards Shreya This e-mail and any files transmitted with it are for the sole use of the intended recipient(s) and may contain confidential and privileged information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. Any unauthorised review, use, disclosure, dissemination, forwarding, printing or copying of this email or any action taken in reliance on this e-mail is strictly prohibited and may be unlawful.
