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

[koven]

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