Thanks Bruno. Okay, I figured it out. I'm not sure if I used an out-of-date web2py/uwsgi/ngninx install script, but that script does not mention another file /usr/share/uwsgi/conf/default.ini
This file sets the number of workers to 2 and it overwrites the web2py configuration file /etc/uwsgi/apps-available/web2py.xml --
