That's simply not true. Yes you have to be smart and know which Python libraries can block (typically those that do their network calls in C, or those that do d

That's simply not true. Yes you have to be smart and know which Python libraries can block (typically those that do their network calls in C, or those that do disk I/O). In practice however this is not a difficult task. After writing several major projects with gevent, all of which make several thousands of network requests per minute, I have to say that it's a pleasure to use. Not magic, but very useful. I have written non-trivial apps with Twisted, and dabbled with Tornado. Gevent avoids all of the "inside out" coding in an elegant way.