This is happening because you have many reducers running, only one of which
gets any data.
Since you have combiners, this probably isn't a problem. That reducer
should only get as many records as you have maps. It would be a problem if
your reducer were getting lots of input records.
You can avoid this by setting the number of reducers to 1.
On 1/15/08 1:17 PM, "Vadim Zaliva" <[EMAIL PROTECTED]> wrote:
> Hi!
>
> I have a novice question. I have data consisting of (Text, Long)
> tuples. I need to calculate sum
> of the values. The way I am achieving it now is mapping Text key to a
> constant value Text("Total") and using
> LongSumReducer as both Combiner and Reducer. It seems to be working
> except that I get many 0-bytes
> output files and just one non-empty file with the actual result. If
> there is a way to avoid creation
> of these empty files? Thanks!
>
> Vadim
>
