Hello,
I would be grateful if someone could shed a light to the following:
Each M/R map task is reading data from a separate region of a table.
From the jobtracker 's GUI, at the map completion graph, I notice that
although data read from mappers are different, they read data
sequentially - like the table has a lock that permits only one mapper to
read data from every region at a time.
Does this "lock" hypothesis make sense? Is there any way I could avoid
this useless delay?
Thanks in advance and regards,
Ioakim
