Simon Willison’s Weblog

Python 3.14. This year's major Python version, Python 3.14, just made its first stable release!

As usual the what's new in Python 3.14 document is the best place to get familiar with the new release:

The biggest changes include template string literals, deferred evaluation of annotations, and support for subinterpreters in the standard library.

The library changes include significantly improved capabilities for introspection in asyncio, support for Zstandard via a new compression.zstd module, syntax highlighting in the REPL, as well as the usual deprecations and removals, and improvements in user-friendliness and correctness.

Subinterpreters look particularly interesting as a way to use multiple CPU cores to run Python code despite the continued existence of the GIL. If you're feeling brave and your dependencies cooperate you can also use the free-threaded build of Python 3.14 - now officially supported - to skip the GIL entirely.

A new major Python release means an older release hits the end of its support lifecycle - in this case that's Python 3.9. If you maintain open source libraries that target every supported Python versions (as I do) this means features introduced in Python 3.10 can now be depended on! What's new in Python 3.10 lists those - I'm most excited by structured pattern matching (the match/case statement) and the union type operator, allowing int | float | None as a type annotation in place of Optional[Union[int, float]].

If you use uv you can grab a copy of 3.14 using:

uv self update
uv python upgrade 3.14
uvx python@3.14

Or for free-threaded Python 3.1;:

uvx python@3.14t

The uv team wrote about their Python 3.14 highlights in their announcement of Python 3.14's availability via uv.

The GitHub Actions setup-python action includes Python 3.14 now too, so the following YAML snippet in will run tests on all currently supported versions:

strategy:
  matrix:
    python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
steps:
- uses: actions/setup-python@v6
  with:
    python-version: ${{ matrix.python-version }}

Full example here for one of my many Datasette plugin repos.

# 4:10 am / gil, open-source, python, github-actions, psf, uv

Why NetNewsWire Is Not a Web App. In the wake of Apple removing ICEBlock from the App Store, Brent Simmons talks about why he still thinks his veteran (and actively maintained) NetNewsWire feed reader app should remain a native application.

Part of the reason is cost - NetNewsWire is free these days (MIT licensed in fact) and the cost to Brent is an annual Apple developer subscription:

If it were a web app instead, I could drop the developer membership, but I’d have to pay way more money for web and database hosting. [...] I could charge for NetNewsWire, but that would go against my political goal of making sure there’s a good and free RSS reader available to everyone.

A bigger reason is around privacy and protecting users:

Second issue. Right now, if law enforcement comes to me and demands I turn over a given user’s subscriptions list, I can’t. Literally can’t. I don’t have an encrypted version, even — I have nothing at all. The list lives on their machine (iOS or macOS).

And finally it's about the principle of what a personal computing device should mean:

My computer is not a terminal. It’s a world I get to control, and I can use — and, especially, make — whatever I want. I’m not stuck using just what’s provided to me on some other machines elsewhere: I’m not dialing into a mainframe or doing the modern equivalent of using only websites that other people control.

# 4:12 pm / apple, brent-simmons, macos, netnewswire, ios

Python 3.14 Is Here. How Fast Is It? (via) Miguel Grinberg uses some basic benchmarks (like fib(40)) to test the new Python 3.14 on Linux and macOS and finds some substantial speedups over Python 3.13 - around 27% faster.

The optional JIT didn't make a meaningful difference to his benchmarks. On a threaded benchmark he got 3.09x speedup with 4 threads using the free threading build - for Python 3.13 the free threading build only provided a 2.2x improvement.

# 6:36 pm / gil, performance, python