Build Your Own Async

David Beazley builds an asynchronous concurrency framework from scratch in Python using callbacks, generators, and coroutines.

Screencast based on a workshop originally presented at PyCon India, Chennai, October 14, 2019. Code samples at: gist.github.com/dabeaz/f86ded8d61206c757c5cd4dbb5109f74 This workshop is about the low-level foundations and abstractions for asynchronous programming in Python. It's a bit unusual in that rather than starting with traditional topics such as non-blocking I/O or sockets, it instead focuses on the core problem of implementing concurrency in lieu of threads. The first part illustrates the process of providing concurrency with callback functions and continuations. The second part, illustrates concurrency using generators and coroutines. At the end, I show how both callback-based and coroutine-based concurrency can be made to co-exist in the same program. The workshop does not focus on the specific implementation details of any one async library (i.e., asyncio, curio, etc.). Instead it is about core concepts. A goal of the workshop is to make it easier to understand the implementation of async libraries and their associated complexities. If you liked this you might enjoy one of my courses. dabeaz.com/courses.html