Simon Willison’s Weblog

Items tagged async in 2020

Filters: Year: 2020 × async ×

datasette-ripgrep: deploy a regular expression search engine for your source code

This week I built datasette-ripgrep—a web application for running regular expression searches against source code, built on top of the amazing ripgrep command-line tool.

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Inevitably we got round to talking about async. As much of an unneeded complication as it is for so many day-to-day use-cases, it’s important for Python because, if and when you do need the high throughput handling of these io-bound use-cases, you don’t want to have to switch language. The same for Django: most of what you’re doing has no need of async but you don’t want to have to change web framework just because you need a sprinkling of non-blocking IO.

Carlton Gibson # 27th September 2020, 3:09 pm

The “await me maybe” pattern for Python asyncio

I’ve identified a pattern for handling potentially-asynchronous callback functions in Python which I’m calling the “await me maybe” pattern. It works by letting you return a value, a callable function that returns a value OR an awaitable function that returns that value.

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Waiting in asyncio. Handy cheatsheet explaining the differences between asyncio.gather(), asyncio.wait_for(), asyncio.as_completed() and asyncio.wait() by Hynek Schlawack. # 26th May 2020, 3:28 pm

Django: Added support for asynchronous views and middleware (via) An enormously consequential feature just landed in Django, and is set to ship as part of Django 3.1 in August. Asynchronous views will allow Django applications to define views using “async def myview(request)”—taking full advantage of Python’s growing asyncio ecosystem and providing enormous performance improvements for Django sites that do things like hitting APIs over HTTP. Andrew has been puzzling over this for ages and it’s really exciting to see it land in a form that should be usable in a stable Django release in just a few months. # 19th March 2020, 3:43 am

Async Support—HTTPX (via) HTTPX is the new async-friendly HTTP library for Python spearheaded by Tom Christie. It works in both async and non-async mode with an API very similar to requests. The async support is particularly interesting—it’s a really clean API, and now that Jupyter supports top-level await you can run ’(await httpx.AsyncClient().get(url)).text’ directly in a cell and get back the response. Most excitingly the library lets you pass an ASGI app directly to the client and then perform requests against it—ideal for unit tests. # 10th January 2020, 4:49 am