A couple of the components used are actually already open-source:

https://github.com/esnme/ultrajson - Super-fast JSON serializer.

https://github.com/esnme/locust - Scalable load testing tool capable of simulating millions of users.

https://github.com/esnme/amysql - 100% async/event driven MySQL driver.

https://github.com/hjlarsson/gevent-memcache - memcached driver for gevent.