When I system.out.println() in a map or reduce, where does it go?

[David Coe <da...@chalklabs.net>]

I've noticed that if I put a system.out.println in the run() method I
see the result on my console.  If I put it in the map or reduce class, I
never see the result.  Where does it go?  Is there a way to get this
result easily (eg dump it in a log file)?

David

Re: When I system.out.println() in a map or reduce, where does it go?

[Tom White <to...@gmail.com>]

You can also see the logs from the web UI (http://<jobtracker>:50030
by default), by clicking through to the map or reduce task that you
are interested in and looking at the page for task attempts.

Tom

On Wed, Dec 10, 2008 at 10:41 PM, Tarandeep Singh <ta...@gmail.com> wrote:
> you can see the output in hadoop log directory (if you have used default
> settings, it would be $HADOOP_HOME/logs/userlogs)
>
> On Wed, Dec 10, 2008 at 1:31 PM, David Coe <da...@chalklabs.net> wrote:
>
>> I've noticed that if I put a system.out.println in the run() method I
>> see the result on my console.  If I put it in the map or reduce class, I
>> never see the result.  Where does it go?  Is there a way to get this
>> result easily (eg dump it in a log file)?
>>
>> David
>>
>

Re: When I system.out.println() in a map or reduce, where does it go?

[Tarandeep Singh <ta...@gmail.com>]

you can see the output in hadoop log directory (if you have used default
settings, it would be $HADOOP_HOME/logs/userlogs)

On Wed, Dec 10, 2008 at 1:31 PM, David Coe <da...@chalklabs.net> wrote:

> I've noticed that if I put a system.out.println in the run() method I
> see the result on my console.  If I put it in the map or reduce class, I
> never see the result.  Where does it go?  Is there a way to get this
> result easily (eg dump it in a log file)?
>
> David
>

reply: When I system.out.println() in a map or reduce, where does it go?

[koven <ko...@gmail.com>]

The best method is find them in web.
If hadoop-default.xml,find it
<property>
  <name>mapred.job.tracker.http.address</name>
  <value>0.0.0.0:50030</value>
  <description>
    The job tracker http server address and port the server will listen on.
    If the port is 0 then the server will start on a free port.
  </description>
</property>
If you open the port 50030,then you can check the System.out.println() at
the web

Re: When I system.out.println() in a map or reduce, where does it go?

[Edward Capriolo <ed...@gmail.com>]

Also be careful when you do this. If you are running map/reduce on a
large file the map and reduce operations will be called many times.
You can end up with a lot of output. Use log4j instead.

Re: When I system.out.println() in a map or reduce, where does it go?

[Ravion <ra...@gmail.com>]

Please check userlogs directory
----- Original Message ----- 
From: "David Coe" <da...@chalklabs.net>
To: <co...@hadoop.apache.org>
Sent: Thursday, December 11, 2008 5:31 AM
Subject: When I system.out.println() in a map or reduce, where does it go?


> I've noticed that if I put a system.out.println in the run() method I
> see the result on my console.  If I put it in the map or reduce class, I
> never see the result.  Where does it go?  Is there a way to get this
> result easily (eg dump it in a log file)?
> 
> David