On Jan 5, 2010, at 9:13 AM, psdc1978 wrote:
1 - I would like to see what is output that the Maps is doing on my example. Is it possible to put hadoop only running Map tasks, excluding the Reduce tasks?
Set the number of reduce tasks to 0.
2 - The output of the Maps is written into a temporary file?
Each map's unsorted output will be sent to the OutputFormat, which writes it to the output directory.
3 - How the output of the maps is passed to the reduce tasks? Is using a socket or reading a file in the disk?
MapReduce does not assume any shared disks between machines. The map outputs are transfered via http.
-- Owen
