On Mon, 3 Mar 2008, Paco NATHAN wrote:
Just a side note:
If a combiner is used, that usually would be considered as part of the
cost of the mapper phase, right?
Yes.
On Mon, Mar 3, 2008 at 12:17 PM, Amar Kamat <[EMAIL PROTECTED]> wrote:
Currently reducers go through 2 phases
1) Shuffle phase : copying the map outputs
2) Reduce phase : Actual reducing
So by starting the reducers we actually start the shuffle phase. Ideally
the shuffle phase should interleaved with the map phase.
Amar
On Mon, 3 Mar 2008, Marc Harris wrote:
> I noticed when reading http://wiki.apache.org/hadoop/HardwareBenchmarks
> the following comment:
>
> "I ran into some odd behavior on Herd2 where if i [ . . . ] the reducers
> don't start until the mappers finish, slowing the job significantly."
>
