Problem with rendering tiles with mapnik

Hi all,
I have downloaded the file tunisia.osm and with the osm2pgsql i put the data into a postgres data base.
I have followed the instruction how to change the set-mapnik-dev and i have executed the following commands :

source set-mapnik-env
./customize-mapnik-map >$MAPNIK_MAP_FILE
./z0_generate_tiles.py

But the problem is that it seems that the command ./z0_generate_tiles.py lead to an** infinite execution.**
I need your help please.
Thanks.

I’ve never used z0_generate_tiles.py but please tell us in what way it will execute infinitly?