2023 Core Dev Sprint in Brno, October 9-14

  • Sep 18-22
  • Sep 25-29
  • Oct 2-6
  • Oct 9-14
  • Oct 16-20
  • Oct 23-28
  • Oct 30-Nov 3
  • Nov 6-10
  • Nov 13-17

0 voters

As of April 13, the most likely date is October 2-6.

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@encukou Do you have an estimate on when a final date will be selected? Looks like we have 3 weeks that are all tied at 80%.


I’ll close the polls tomorrow (Tuesday).

I’m guessing it’ll be a week or two before I can get a reservation confirmed.

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Mark your calendars! The Sprint will be on October 9-14.

You can RSVP early here: https://forms.gle/BeMfbB6QPJAXB6939, and change your answers later.

I’ll get in touch with the PSF about travel/accomodation reimbursement. Don’t book travel yet if you need PSF money.

The sprint intended for core devs. (If you’re not one yet, you’ll need an invitation from one, and I’ll need to confirm the invitation.)
And it’s in-person only. (If you can’t make it, we can’t provide a better experience than Discord and ad-hoc video calls with attendees.)


I just RSPVed hope it wasnt too late. I think my brain is getting old and failing to keep up with discuss.

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Definitely not too late!

But, everyone, if you’re thinking about coming, please do fill out the form. Even uncertain answers help planning. You can change your mind later.


I’ll meet with the PSF on Thursday (June 1) to discuss budgets and reimbursements.
If you can, please fill the form by then to help with planning. It should only take a few minutes.

  • You can change answers later (e.g. “Are you coming” from “most likely” to “no”)
  • Don’t sweat the cost estimation yet, right now I’m looking at the continent you’re from.
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Budget and booking

The PSF is working on a budget. This year, it looks like the PSF will book a hotel, hopefully with a group discount.

C-API mini-event

I’m planning a C-API “summit” on the first day – in person discussion about where we are and where to go. Exact agenda TBD.
People from the HPy project might be sprinting the week before us. Some are invited to the sprint itself, but any others will be welcome in the venue for the C-API discussions.

Other mini-events

Want a mini-event at the sprint? You can just announce it there, but it’s better to let me know in advance so I can prepare anything extra you’ll need (reserve a room, let in guests, set up recording…)

Here’s a very rough tally of what people want to work on. It includes those who aren’t sure if they’ll come:

  • C API ×7
  • Performance ×5
  • Docs ×5
  • platform support (Wasi, POSIX, macOS, …) ×4
  • asyncio ×3
  • typing ×3
  • extensions (importing, building) ×3

Visa and Invitation letters

The PSF is happy to provide visa/invitation letters if you need them, and Phyllis set up a form for collecting the necessary information.
I’ve sent a link to the form to everyone who answered they might need it. If you didn’t get the e-mail and want the link, let me know!


  • Citizens of the US, EU and Canada (and several other countries) should not need a Schengen visa.
  • EU’s planned travel authorisation system, ETIAS, has been delayed to 2024. No need to worry about it.

I have some good news, and some bad ones.

The good news is that the sprint is happening. Book your flights!
Generally, you’ll want to fly to either Vienna (VIE) or Prague (PRG), arrive at the airport on Sunday the 8th at latest, and depart Saturday at earliest.
The best way to get from there to the sprint is by train; I’ll provide instructions next week.

Now the bad news: accomodation. The PSF didn’t manage to get a hotel block, despite trying since late May. I thought everything’s on track, so I brought it up too late, and… yesterday I found out that there’s a giant fair overlapping with the sprint, and most hotels in the city are sold out.

Lessons to be learned all around. Thanks to everyone who helped me look for solutions!

That gives me/us two options. I’d like to judge your interest here; the poll will be open until Monday.


We sprint in Brno as originally planned. You find and book your own hotel, AirBnB or apartment. Couch-surf if that’s your thing.
The PSF will reimburse up to $80/night, and according to an AirBnB search there are enough places in that price range within ~20 min from Red Hat. Everyone can get a room.
I’ll provide more info and instructions early next week, and I’ll help in any way I can.

This would be much easier for me to organize – I know the city [1] and many people in it.

Somewhere else

The other option is sprinting in another city, in a hotel with a meeting room.
I don’t think it would be that different for most of you, travel-wise: a few hours more (or less) to get there and back on the weekend before and after. But it’d be an unfamiliar place for everyone.


The poll is public. If you’re not comfortable with that (or can’t vote in this category), feel free to send me a message.

  • Brno!
  • I’d prefer Brno
  • Don’t care
  • I’d prefer a hotel
  • Definitely a hotel for me
0 voters

Any questions?

I’ll try to be as online as I can this weekend, and I’ve asked @Phyllis from the PSF to keep an eye here as well.

  1. Except for its giant engineering fair…… ↩︎


The poll option I’d prefer is “just wanting a concrete answer as to the destination” because flight prices go up non-linearly and not knowing means I can’t book anything…

Has anyone already booked their non-refundable travel?


You’ll get your answer Monday or Tuesday.
Whatever gets chosen, Vienna and Prague will be the international airports for it.


Good news! We have blocked 20 rooms at Hotel Palacký ***, a 10-minute walk from the venue. (Their website is out of date and badly translated, and you can’t get a reservation online – which worked in our favour!)

So, we’re staying in Brno, and I will manage the reservation for most of you.

Please update your answers on the form by Thursday, 12:00 noon UTC. (Sorry for the tight deadline!)
The link should be in your inbox: search for google forms sprint 2023. Or go here if you haven’t signed up yet.

I’ve started an information document/FAQ for the sprint. Please request permission if you don’t have it.
I’ll add info on trains from airports later this week. (tldr: allow ~4 hours for the trip from Prague/Vienna)

As always, let me know if you have any questions.


If you haven’t updated your answers, please do that ASAP.
I need info for reserving the hotel by tomorrow 12:00 UTC. After that you can still get a room but the PSF might not reimburse it.

Let me know if you have any questions or trouble – I’ll be happy to help any way I can, but I need to know what your situation is.

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Hotel reimbursement

A correction: if you’re not staying at hotel Palacký, the PSF will reimburse up to $80/night/person (Sunday to Saturday, Oct 4-14).

Hotel Palacký

If you selected “make a binding reservation” in the form, you have a room reserved at Hotel Palacký.
If you’re arriving in a larger group, you can print their registration card and fill it in advance to speed up check-in. (Yes, they use dead trees.)
If you want to, you can claim a room number in the shared travel plans, linked from the info document.

Events & presentations

If you want to introduce a topic, have a recorded/streamed discussion, present with slides, etc. it’s best to let me know in advance.

Here’s another rough tally of what people will want to work on:

  • C API ×7 (mini-summit on Monday)
  • Platforms (Wasm, mobile, macOS, Posix) ×5
  • Performance ×4 (presentation on ~Tuesday)
  • Docs ×4
  • Workflows, tools, infra ×4
  • Asyncio ×4
  • New PEPs ×4
  • Typing ×2
  • Parser ×2
  • (no)GIL ×2
  • Subinterpreters ×2

Guest list

I will request building & Wi-Fi access next week, using names & e-mails from the form.
You might get an e-mail asking you to pre-register, if you don’t do that the system will ask you for info when you arrive.
(I haven’t used the system before and I don’t really know what it will do. If you have any questions about that mail, please forward it to me after you get it.)


If you want a parking spot at the venue, please let me know this week, if you haven’t already.
(I do not recommend renting a car for Brno.)


The sprint is getting near! Are you ready?
Here’s the latest bunch of updates. (Everything is also in the info document).

Power plugs

Plug types E, F, C (French and Schuko) will work.
(Ask Petr if you want to borrow an adapter for a US ungrounded plug or a C5 “mickey mouse” connector.)


Red Hat Brno recently donated almost all of its spare monitors for charity, so I’m is borrowing spare monitors from colleagues.
So far: we’ll have monitors for at about 50% of the people who prefer one. Not great, not terrible.

Thursday Dinner

We have a reservation for Thursday evening at Stopkova plzeňská pivnice (web is Czech only, and we’ll have a custom menu).
I might not join for family reasons, so a few people from Red Hat’s Python-maint team are organizing, and will join, the dinner.

Food money

The PSF is planning to reimburse USD $30 (~700 CZK) per day for food (as per diems, so you don’t need to save receipts).

Food allergens

In most restaurant menus, allergens are indicated by the number codes below. If you’re sensitive to something, I recommend remembering the number.
(But using these particular numbers is not required by law – if you have a severe allergy you’ll want to ask a Czech speaker to check with the waiter.)

Allergens (click to expand)
  • 1 = Gluten
  • 2 = Crustaceans
  • 3 = Eggs
  • 4 = Fish
  • 5 = Peanuts
  • 6 = Soybeans
  • 7 = Milk
  • 8 = Nuts
  • 9 = Celery
  • 10 = Mustard
  • 11 = Sesame
  • 12 = Sulphur dioxide
  • 13 = Lupin
  • 14 = Molluscs

See you in Brno!


Thank you all for coming! I hope the week was fun and productive for you, and that you got home safely :‍)

Note that sprints are not a place for making decisions. If you cooked up a plan, it’s now time to turn it into a public proposal.
If you have slides or are on recordings you want to share publicly, let me know.

If you weren’t at the sprint, watch for new PEPs!

This sprint felt more about discussions and less about coding and reviewing. Correspondingly, we didn’t make much of a dent in the commit numbers. IMO, that’s not a bad outcome – we can code at home :‍)

For the benefit of future organizers, here’s a copy of the info document, with personal/private info removed: https://docs.google.com/document/d/1vmIJObQ1HESbzwBAI10FRgmoJhzIAtgMo9r1t5B4cFo/edit

Speaking of future organizers: Ideally the next sprint could be in America. Do you want to organize it?

Someone left a black hoodie behind. If it’s yours, let me know.

If I hear nothing in a month I’ll give it to charity.



You can now ask the PSF to reimburse your travel expenses. I sent an email about this to all the sprinters; let me know if you didn’t get it.


If you want to ask for reimbursement but haven’t yet, please do it as soon as possible.

The PSF requests all travel grant requests for this sprint to be received by December 15. We want to reimburse folks as quickly as possible, but also have a December 31 deadline for 2023 expenses.

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