Some news, I’ll be departing the PSF as a staff member at the end of this week.

we must imagine Sisyphus being directed to the boulder corporation’s outsourced mental health support service for up to 2 hours of free counselling per eternity

I’m incredibly excited to serve on this coming term’s Steering Council! Working on CPython has been one of the most rewarding endeavours of my career. I’m so grateful to everyone who voted & honoured that so many placed their trust in me. peps.python.org/pep-8107/

Re-upping this, since it's only available for two days:

it's happening!!! from now until the end of the day on Friday, November 28th (if it’s Friday anywhere, the sale’s still on!), all my pdf zines are 50% off, and print zines are 30% off! wizardzines.com

@tartanllama.xyz Building a Debugger got a review in c't, a big German computer magazine:

lol @hikikomorphism.bsky.social just described Ea-Nāṡir as "CMOT Dibbler (Assyrian Edition)"

Tlingit artist Nicholas Galanin, “Architecture of return, escape (The British Museum)”, a deerskin map a floor plan of the British Museum and possible escape routes for various Indigenous cultural belongings held there.

Interpreter alignment chart

it has been 0 days since I wrote a tiny interpreter to prototype some new database features. you will never regret writing a tiny interpreter

It's spooky season! So I reviewed four great recent scary books: Fiend by @almakatsu.bsky.social Moonflow by @bitterkarella.bsky.social Slashed Beauties by A Rushby You Weren't Meant to be Human by @ajwhiteauthor.bsky.social www.washingtonpost.com/books/2025/1...

📣 The “People from PSF” interview series continues! 🐍💬Meet the people behind the @python.org staff, directors & contributors making the magic happen. 💟 Meet Deb Nicholson @eximious.bsky.social 🔗Read the full interview 👇 dennyperez.dev/projects/psf... #Python #PyLadies #PSF #PeopleFromPSF

The SPy project is kicking off community calls! 🎙️ Join us tomorrow (Oct 7th, 17:30 CEST) on Discord to chat, ask questions, and meet other SPy folks. Everyone’s welcome! 💚 🥸 Discord link: discord.gg/ZN4afjvq?eve... Google calendar link: lnkd.in/d3U62QNn

Last week I was lucky to take part in the CPython Core Dev Sprint. This is a summary of what I did, including an annotated and extended version of my talk on tracing JITs in real-world Python scenarios, plus some comparisons between PyPy’s JIT and CPython’s new JIT. 👉 antocuni.eu/2025/09/24/t...

hey we have a lot of fun here, living in a fascist dystopia and goofing on the very real lives being ruined by the state, it's great, things are fine, we love it! Why not enjoy the end of civilization with a good book? why not do it with MY book?? www.hachettebookgroup.com/titles/bitte...

2008, I am driving back across the Canadian border from Montreal with @stillsostrange.bsky.social and @batwrangler.bsky.social in my tiny1998 Honda Civic sedan.

happy analog gender week nerds 💛🤍💜🖤

OMG no!!! I still think Knuth's deep dive from "I want to write about algorithms" to "I need typesetting software" to "I need fonts" to "I need font software" to "I need software to write software" may be the most epic software exploration in human history, and kids these days have NO IDEA about it.

New blog post by @cfbolz.bsky.social: "How fast can the RPython GC allocate?" pypy.org/posts/2025/0...

"How slow is the tracing interpreter of PyPy's meta-tracing JIT?" cfbolz.de/posts/speed-... Spoiler: for the microbenchmark I tried, the slowdown of the meta-tracing interpreter is about 900x

@keleshev.com not sure whether you already saw, but Compiling to Assembly from Scratch got a review in c't 9/25 (the largest German IT magazine)

We just merged an improvement to the PyPy JIT heap optimizations: type based alias analysis for Python instances. Work was done by @cfbolz.bsky.social and their student Nico Rittinghaus.

'Doing the Prospero-Challenge in RPython' new blog post on the PyPy blog: pypy.org/posts/2025/0...

Fast on the heels of the last release, I have published a PyPy v7.3.19 bug-fix release with PyPy2.7, PyPY3.10 and a beta-quality PyPy3.11. Please try it out! The complete release note is at doc.pypy.org/en/latest/re...

New blog post by my excellent master student Christoph Jung: "Low Overhead Allocation Sampling with VMProf in PyPy's GC" pypy.org/posts/2025/0... Hopefully the first in a series about his work on a sampling allocation profiler for PyPy

I needed something quick and dirty to count the number of malloc calls in some C programs, and the total size of the allocated memory. @pablogsal.com very helpfully shared some LD_PRELOAD code with me, which solved the problem 🙏 gist.github.com/cfbolz/12ff1...

Since I was now wondering, here's PyPy VS CPython 3.x binary sizes

Interestingly enough PyPy 3.x is mostly smaller than 2.7. E.g. PyPy 3.11 is 58.8 MiB, despite having a bunch more features. I never quite figure out why. Just for comparison, CPython 3.11 is 25.2 MiB.

This is the size of PyPy 2.7, btw. It doesn't make sense to use the 3.x variant for this, because the size of that changes due to newer Python versions being implemented over time.

We don't do this regularly or anything, but every couple of years @cfbolz.bsky.social looks at how the PyPy binary sizes have developed. Looks like an ok balance between occasionally cleaning something up and thereby shrinking the binary; and then slow growth or explicit time/binary-size-tradeoffs.

As a response to these benchmarks, @cfbolz.bsky.social optimized `itertools.islice` for the common case where no step is given, and also for converting large but not very large integers to strings (basically any int that doesn't fit into 64 bits, but is also not really huge, maybe a few words).

The other new feature an implementation of the draft PEP 768, "Safe external debugger interface" (again, Linux only so far). PEP was written by @pablogsal.com et al. It allows you to remotely attach to a running PyPy process and inject Python code into it. doc.pypy.org/en/latest/re...

Here's a screenshot of the Firefox Profiler UI showing VMProf output. The blue functions are native functions, yellow is Python functions and orange jitted functions (no example of that is in the screenshot).

Here's the blog post about the PyPY 7.3.18 release that came out yesterday. Thanks to @matti-p.bsky.social, our release manager! This the first version with 3.11 support (beta only so far). Two cool other features in the thread below. pypy.org/posts/2025/0...

The PyPy project now has an account here, please everyone go follow it so we can stop using Twitter: @pypyproject.bsky.social

PyPy 7.3.18, with Python3.11, 3.10, 2.7 is released. See the release note at doc.pypy.org/en/latest/re...

Today is my 20th anniversary working on PyPy! At least I sent my first mail to pypy-dev 20 years ago: mail.python.org/archives/lis... Still enjoying working on it immensely! And have lots of ideas what I want to do when I get around to things.

PL researchers: noooo, you can't have lazyiness and imperative semantics, that sounds insane Statisticians using R: hahah tables go brrrr

👋👋 I'm not sure I'm actually here. I'm suffering from acute social media platform overload 🤷‍♀️. Might repost things occasionally, we'll see.

Last year I asked a question about the state of tracing JITs, and it led to a wonderful exchange. @cfbolz.bsky.social has written a terrific summary that captures a lot of folk knowledge that would otherwise be lost. Thanks! pypy.org/posts/2025/0...