From the gevent website:
gevent is a coroutine-based Python networking library that uses greenlet to provide a high-level synchronous API on top of the libev event loop.
- Fast event loop based on libev (epoll on Linux, kqueue on FreeBSD).
- Lightweight execution units based on greenlet.
- API that re-uses concepts from the Python standard library (for example there are Events and Queues).
- Cooperative sockets with SSL support »
- DNS queries performed through threadpool or c-ares.
- Monkey patching utility to get 3rd party modules to become cooperative