export PYTHONUSERBASE=$PWD/py-env
pip2 install --user -r requirements.txt

If you never had postgres setup:

sudo -u postgres initdb --locale en_US.UTF-8 -D /var/lib/postgres/data
sudo systemctl start postgresql

For mysql/mariadb just start it with sudo systemctl start mysqld, it'll connect using root on localhost which should work out of the box.

Run the app:

uwsgi --ini uwsgi.ini --thr # to work with 1000 thread workers
uwsgi --ini uwsgi.ini --gev # to work with 1000 async gevent cores

Add --env DB=MYSQL to run tests against MySQL/MariaDB (using oursql + greenify).

Test requests:

time curl localhost:8080 -i & \
time curl localhost:8080 -i & \
time curl localhost:8080 -i & \
wait

The threading library must be patched when using gevent with SQLAlchemy, since the connection pool uses thread locks. Those locks will deadlock (huh) the interpreter udner gevent if not patched with gevent.monkey.patch_thread(). SQLAlchemy before 0.9.3 didn't have those locks, but it probably would fail strangely when used with normal threads.