This version includes a new RWLock. Further development of Toro's ideas continues in Tornado itself.
I merged Toro, my library for coordinating asynchronous coroutines, into Tornado 4.2.
In video form with closed captions, my talk about testing asynchronous Python code.
Event-loop management, error handling, and coroutines as unittests.
Asynchronous Python is more flexible than blocking code, but you need to follow a few rules.
MongoDB's asynchronous interface will require no callbacks in the next release.