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Python Core Sprint 2025

python sprint core-sprint 2025
A group photo of 50 sprinters
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🐍🏃In September, the annual Python Core Sprint was hosted by Arm in Cambridge, UK!

The plan: put 35 core developers and 13 special guests in a room for a week, and see what they cook up.

Monday highlights #

We kicked off the first day with a round of five-word intros (mine: “three”, “dot”, “fourteen”, “release”, “manager”), lots of talks, and lots of discussion about talks:

I did some sprint spring cleaning of our PyPI projects, dropping support for then-almost-EOL Python 3.9:

And because Mariatta wasn’t with us, here’s the all-important Python T-shirt census:

A room of people at desks with monitors. Steve has a mic and is asking a question to Brett who’s standing at and presenting.

The sprint room

Tuesday highlights #

Release day?

I’d originally planned to release Python 3.14.0rc3 on the Tuesday, but the morning was full of presentations, and the afternoon had an early departure for the social event, so I moved it to Wednesday instead.

Tania Allard gave a presentation about the different types of mentorship and how we can improve, followed by an open discussion.

Gregory P. Smith gave a demo on how we can use tools like Claude with CPython.

Tania, Jannis Leidel, Carol Willing and I discussed the User Success Workgroup and we came up with some ideas on next steps.

We ended the day with a punting tour on the river Cam and dinner at Jesus College, thank you, Arm!

And Thomas Wouters gave a fun session of his Feuding Pythonistas game (spoiler: people are wrong on the internet).

Python/tech t-shirt census:

People sitting in a small boat, with a man standing at the back with a long pole in the water, in front of grand Cambridge college

Punting on the Cam

Wednesday highlights #

Release day?

The Steering Council asked for an extra day to decide about a possible typing revert (python/steering-council#307), so not today.

Lightning talks:

Carol, Adam, Thomas, Petr Viktorin and I discussed a number of docs topics.

I released the Python Docs Sphinx Theme with more translations.

We had a Q&A session with the Steering Council, three in-person and two joining remotely.

Jacob Coffee and I looked into upgrading the Python Insider and PSF blogs into something a little more modern.

T-shirt census:

Steering Council Q&A: Greg, Pablo and Donghee on stools and Barry and Emily on screen.

The Python Steering Council

Thursday highlights #

Release day? Yes!

The Steering Council decided not to revert, so full steam ahead with the release.

Savannah Ostrowski, release manager for 3.16 and 3.17, shadowed to see what the process looks like (not as bad as it looks like in PEP 101).

Time for a couple of quick PRs and an interview with Pablo Galindo Salgado and Łukasz Langa on the core.py podcast, along with 29 others!

T-census:

The 3.14 release room, two laptops on a table and the release CI build shown on a screen. The laptop with the “365 PARTYGIRL” sticker isn’t mine.

The 3.14.0rc3 release in progress

Friday highlights #

I went to Manchester to attend PyCon UK. Some highlights:

The conference also included sprints, and Adam and I ran the CPython sprint. We had a big table full of contributors and a few made their very first contributions, which is always rewarding for all involved!

Another roomful of people working at laptops around tables

PyCon UK sprint

Some numbers for me during the week:

  • Python release candidates released: 1
  • Issues created: 1
  • PRs created: 8
  • Issues closed: 7
  • PRs merged: 28
  • PRs closed: 1
  • Total issues involved with: 18
  • Total PRs involved with: 70
  • Repositories affected: 19

Thank you #

Huge thanks to Diego Russo and Arm for arranging and hosting us. The core sprint is always a highlight of the year and an incredibly productive week.

Read writeups by Diego and Antonio, and I recommend listening to Łukasz and Pablo’s core.py podcast for interviews with 18 (part one) and 12 sprinters (part two). They’re long, but it’s fascinating to hear all the different things everyone is working on.

Header photo by Arm