hypercorn VS trio

for those wishing to use http3 with a Python web framework, the ASGI hypercorn[1] currently supports it.

made a Django example last week with a sample client based on the examples from aioquic[2]: https://github.com/djstein/django-http3-example

this example also includes the first pass at async Django REST Framework using adrift[3] based on these GitHub issues:

- https://github.com/encode/django-rest-framework/pull/8617

- https://github.com/encode/django-rest-framework/issues/8496

sources

[1]: https://github.com/pgjones/hypercorn

[2]: https://github.com/aiortc/aioquic

[2]: https://github.com/em1208/adrf

Incidentally, the alternative event loop implementation trio in python does not have "gather", you also need channels, and it's a deliberate design choice - there is some discussion about that in this ticket https://github.com/python-trio/trio/issues/2188

trio – a friendly Python library for async concurrency and I/O

trio. the best code, the best documentation, awesome community.

I'll +1 the Trio shoutout [1], but it's worth emphasizing that the core concept of Trio (nurseries) now exists in the stdlib in the form of task groups [2]. The article mentions this very briefly, but it's easy to miss, and I wouldn't describe it as a solution to this bug, anyways. Rather, it's more of a different way of writing multitasking code, which happens to make this class of bug impossible.

[1] https://github.com/python-trio/trio

[2] https://docs.python.org/3/library/asyncio-task.html#task-gro...

It's similar to manual memory management.

Structured concurrency is one approach to solving this problem. In a structured concurrency a promise would not go out of scope unhandled. Not sure how you would add APIs for it though.

See Python's trio nurseries idea which uses a python context manager.

https://github.com/python-trio/trio

I'm working on a syntax for state machines and it could be used as a DSL for promises. It looks similar to a bash pipeline but it matches predicates similar to prolog.

In theory you could wire up a tree of structured concurrency with this DSL.

https://github.com/samsquire/ideas4#558-assign-location-mult...

Not complete - doesn't include Task Groups [1]

In fairness they were only included in asyncio as of Python 3.11, which was released a couple of weeks ago.

These were an idea originally from Trio [2] where they're called "nurseries" instead of "task groups". My view is that you're better off using Trio, or at least anyio [3] which gives a Trio-like interface to asyncio. One particularly nice thing about Trio (and anyio) is that there's no way to spawn background tasks except to use task groups i.e. there's no analogue of asyncio's create_task() function. That is good because it guarantees that no task is ever left accidentally running in the background and no exception left silently uncaught.

[1] https://docs.python.org/3/library/asyncio-task.html#task-gro...

[2] https://github.com/python-trio/trio

[3] https://anyio.readthedocs.io/en/latest/

One consideration I'd like to see in an article like this is backpressure support (https://lucumr.pocoo.org/2020/1/1/async-pressure/). A key component of choosing any approach is to consider the ecosystem of libraries. So if going for async, a library like https://github.com/python-trio/trio looks promising, is being actively developed, and seems to have an active community around it.

> I do not recall that the author of this pamphlet has ever done much

He made the Trio library, which is ridiculously good and also ridiculously hard to implement (just look at this issue [1] for example where he carefully examines the three (!) different async APIs on Windows). Lessons from it are being folded back into the asyncio library in core Python (e.g. exception groups) everyone benefits even if they don't use Trio directly.

[1] https://github.com/python-trio/trio/issues/52