FAQ
Hi everyone,

I am new to it, and want to do some debug/log. I'd like to check what the value is for each mapper execution. If I add the following code in bold, where can I find the log info? If I can't do it in this way, how should I do?

public void map(Object key, Text value, Context context
) throws IOException, InterruptedException {
StringTokenizer itr = new StringTokenizer(value.toString());
System.out.println(value.toString);
while (itr.hasMoreTokens()) {
word.set(itr.nextToken());
context.write(word, one);
}
}
}

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  • Harsh J at Jul 28, 2011 at 7:01 am
    Task logs are written to userlogs directory on the TT nodes. You can
    view task logs on the JobTracker/TaskTracker web UI for each task at:

    http://machine:50030/taskdetails.jsp?jobid=<JOBID>&tipid=<TASKID>

    All of syslogs, stdout and stderr logs are available in the links to
    logs off that page.

    2011/7/28 Daniel,Wu <hadoop_wu@163.com>:
    Hi everyone,

    I am new to it, and want to do some debug/log. I'd like to check what the value is for each mapper execution. If I add the following code in bold, where can I find the log info? If I can't do it in this way, how should I do?

    public void map(Object key, Text value, Context context
    ) throws IOException, InterruptedException {
    StringTokenizer itr = new StringTokenizer(value.toString());
    System.out.println(value.toString);
    while (itr.hasMoreTokens()) {
    word.set(itr.nextToken());
    context.write(word, one);
    }
    }
    }


    --
    Harsh J
  • Devaraj K at Jul 28, 2011 at 7:05 am
    Daniel, You can find those std out statements in "{LOG
    Directory}/userlogs/{task attemp id}/stdout" file.

    Same way you can find std err statements in "{LOG Directory}/userlogs/{task
    attemp id}/stderr" and log statements in "{LOG Directory}/userlogs/{task
    attemp id}/syslog".

    Devaraj K

    -----Original Message-----
    From: Daniel,Wu
    Sent: Thursday, July 28, 2011 11:47 AM
    To: common-user@hadoop.apache.org
    Subject: where to find the log info

    Hi everyone,

    I am new to it, and want to do some debug/log. I'd like to check what the
    value is for each mapper execution. If I add the following code in bold,
    where can I find the log info? If I can't do it in this way, how should I
    do?

    public void map(Object key, Text value, Context context
    ) throws IOException, InterruptedException {
    StringTokenizer itr = new StringTokenizer(value.toString());
    System.out.println(value.toString);
    while (itr.hasMoreTokens()) {
    word.set(itr.nextToken());
    context.write(word, one);
    }
    }
    }

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groupcommon-user @
categorieshadoop
postedJul 28, '11 at 6:17a
activeJul 28, '11 at 7:05a
posts3
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websitehadoop.apache.org...
irc#hadoop

3 users in discussion

Devaraj K: 1 post Harsh J: 1 post Daniel,Wu: 1 post

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