Not sure why the stdout/stderr files in $HADOOP_LOG_DIR/userlogs/xxx
would be empty, but an alternative that I use is the log4j framework
used by Hadoop. You can instantiate it like this:
private static final Log LOG = LogFactory.getLog(YourClass.class);
And then use it like this:
LOG.info("...");
LOG.debug("...");
etc.
If you use this in your map/reduce class, the messages will be in the
logs of individual tasks.
Ed
On Tue, Dec 8, 2009 at 7:14 AM, Kunal Gupta <[email protected]> wrote:
> I am outputting a message to stdout and stderr from inside my MAP
> function.
> but the stdout and stderr files in log folder are empty. I tried looking
> these logfiles from the web UI as well. They are empty only.
>
> Why are these messages not getting printed?
> Alternately, where can i print messages for debugging my MR
> application..?
>
>
