run gunicorn with eventlet

this massively increases the horizontal parallellability by using async workers

manifest-base.yml

@@ -1,7 +1,16 @@
 ---
 
 buildpack: python_buildpack
-command: scripts/run_app_paas.sh gunicorn -c /home/vcap/app/gunicorn_config.py --error-logfile /home/vcap/logs/gunicorn_error.log -w 5 -b 0.0.0.0:$PORT application
+command: >
+  scripts/run_app_paas.sh
+  gunicorn
+  -c /home/vcap/app/gunicorn_config.py
+  --error-logfile /home/vcap/logs/gunicorn_error.log
+  -w 5
+  -b 0.0.0.0:$PORT
+  -k eventlet
+  application
+
 instances: 1
 memory: 1G
 env:

requirements.txt

@@ -13,7 +13,7 @@ pyexcel-ods3==0.5.2
 pytz==2017.3
 gunicorn==19.7.1
 whitenoise==3.3.1  #manages static assets
-
+eventlet==0.22
 notifications-python-client==4.7.1
 
 # PaaS