The wiki (or Hadoop The Definitive Guide) are good ressources.
Mapper is the name of the abstract class/interface. It does not really make
sense to talk about number of mappers.
A task is a jvm that can be launched only if there is a free slot ie for a
given slot, at a given time, there will be at maximum only a single task.
During the task, the configured Mapper will be instantiated.
Number of input splits = no. of map tasks
And generally :
number of hdfs blocks = number of input splits
PS : I don't know if it is only my client, but avoid red when writting a
On Tue, Feb 25, 2014 at 8:49 AM, Dieter De Witte <[EMAIL PROTECTED]> wrote: