Examples, resources, slides, and outline for my python concurrency and coroutines talk.
Presentations of this talk:*
This repository is organized with a release for each instance where the talk was given, in case anyone would like to reference the talk as it was at that time. However, I generally consider the current version to be a better general reference.
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PyTennessee Conference February 4, 2017 - current version
A brief introduction to concurrency and coroutines
This is a beginner-friendly introduction to concurrent programming Using a simple example task, differences in threaded and cooperative approaches to concurrency will be illustrated. The talk will then focus on how coroutines have developed in Python from iteration protocol and generators to the new async/await syntax, and how coroutines can be used with the provisional "asyncio" event loop in the Python standard library. It will be assumed that the listener has a basic understanding of functions, classes, and exceptions in Python, but no prior knowledge of concurrent programming is required.
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Explain the difference between concurrency and parallelism using the example of cooking a traditional US Thanksgiving dinner.
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Motivate with example task of retrieving animal noises from the slow animals API and printing them using animation. Discuss difference between parallelism and concurrency, need for the latter in this situation.
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Explain iteration protocol in python,
__next__and__iter__magic methods, simple example "Countdown" Class implementing the protocol. -
Show equivalent "countdown" generator function using yield statement. Discuss generator as a semicoroutine candidate.
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Discuss PEP342 improvements to generators with examples of generators using results from yield expressions and the send() function.
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Discuss need for delegation to sub-coroutines and PEP380 yield from syntax.
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Introduce new async/await syntax, the separation of coroutines from iterators, and the meaning of "awaitable"
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Introduce the "asyncio" event loop, give simple examples of running on REPL.
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revise concurrent solution to the animals example using coroutines and asyncio.
The actual slides alone don't constitute a resource that one can reasonably follow to understand the talk. I'm working on a set of articles below which explain the basics of concurrency and coroutines in python, along with some extended information that I would have talked about if I had an infinite amount of time to prepare and present the talk:
- What is concurrency?
- Coroutines versus threads (optional/extended)
- Python on the road to coroutines (optional)
- Using coroutines with asyncio
- Writng an asyncronous webservice (extended)
Sections marked optional are not really needed if you want to get started using asyncio and coroutines, but give some extra information on how they are implemented and why one might use them as opposed to other approaches.
Sections marked extended were not presented in the talk.