mapred.map.tasks is rather a hint to InputFormat (
http://wiki.apache.org/hadoop/HowManyMapsAndReduces) and it is ignored in
your case.

You process gz files, and InputFormat has isSplitatble method that for gz
files it returns false, so that each map tasks process a whole file (this
is related with gz files - you can not uncompress a part of gzipped file.
To uncompress it, you must read it from the beginning to the end).
2013/12/11 Dror, Ittay <[EMAIL PROTECTED]>