core.py

Pablo Galindo and Łukasz Langa
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We talk about Python internals, because we work on Python internals. We joke about stuff, because we’re jokers. Episodes between 60 and 90 minutes in length. We’ve done more than a few so far and it doesn’t seem like we’ll be stopping any time soon! Hi Loren!

  1. 28 Jul

    Episode 30: Live from EuroPython, an Interview with Guido van Rossum

    This one is a short one. But it's also a big one. We'd invite you to listen to it, but you don't need to follow us. You don't need to follow anybody! You've got to think for yourselves! You're all individuals! ## Timestamps (00:00:00) INTRO (00:00:36) PART 1: GUIDO VAN ROSSUM (00:01:09) Monty Python reference only GvR understood (00:01:27) Math Olympiad anniversary (00:03:31) Silly hats (00:05:20) perchance (00:09:51) PR OF THE WEEK (not really) (00:11:04) The Grail Web Browser (00:14:31) Generational gaps (00:17:24) Changes in beliefs (00:21:43) Pablo Galindo Salgado was never right (00:23:11) Aesthetics in coding (00:29:16) Rietveld (00:34:14) VScode is the new Emacs (00:35:41) On recognition outside of tech (00:38:11) Taste in music (00:39:51) Cameo in a movie? (00:40:52) OUTRO

  2. 08/03/2025

    Episode 19: Async hacks, unicorns and velociraptors

    In this asynchronous episode we're interviewing a fellow core developer Yury Selivanov to talk about asyncio's past and future, composable design, immutability, and databases you'd actually like using. We also broke the 2-hour episode barrier! ## Timestamps (00:00:00) INTRO (00:01:33) PART 1: INTERVIEW (00:02:27) What drives you? (00:04:47) How do you choose what to work on? (00:08:10) Hyperfocus (00:09:28) Things from Rust that Python could use (00:14:50) Nothing is sacred when you depend on glibc (00:18:47) TypeScript typing is god-tier (00:22:04) Adding async and await to Python (00:34:11) Adding new keywords to the language (00:41:17) Jumping into a new codebase (00:49:22) Any design regrets? (00:58:46) Contextvars (01:10:40) Is the frozenmap PEP happening? (01:19:21) uvloop (01:23:25) What makes Gel lovable? (01:39:57) PART 2: PR OF THE WEEK (01:47:08) Saturday talks at PyCon should be fun (01:50:35) PART 3: WHAT'S GOING ON IN CPYTHON (01:50:47) Ken Jin's tail-call interpreter (01:55:05) Barney Gale's glob.glob() optimization (01:55:43) Brandt's boolean guards to narrow types to values in the JIT (01:56:33) Mark Shannon's stack limits implemented with addresses, not counters (01:58:34) Brandt's removal of _DYNAMIC_EXIT (01:58:53) Mark Shannon's async for branches instrumented (01:59:36) Free-threading changes (01:59:58) Sam Gross' regression tests can now run in --parallel-threads (02:00:34) Tomasz Pytel's thread safety crusade (02:01:01) Xuanteng Huang's __annotations__ race fix (02:01:11) Kumar's per-thread linked lists for tasks (02:02:54) Serhiy's crashes related to PySys_GetObject() fixed (02:03:22) Sam's usage of stack pointers in thread stack traversal (02:03:38) Dino Viehland's lock avoidance during object cleanup (02:04:23) OUTRO

  3. 24/01/2025

    Episode 18: Reference Counting

    After we talked about memory allocation in Python back in Episode 16, we're ready to complain, uh, explain reference counting. Or at least throw a bunch of reference counting facts at you. Plus a big assortment of recent Python changes. You ready? ## Timestamps (00:00:00) INTRO (00:04:17) PART 0: SPORTS NEWS (00:06:53) PART 1: REFERENCE COUNTING (00:08:28) New segment of 2025 (00:13:54) C++ is asymptotic Python (00:15:37) Is Rust game yet? (00:18:01) Names (00:20:25) Breaking the law (00:23:08) sys.getrefcount() (00:25:21) Pedantic Pablo (00:26:06) sys.gettotalrefcount() (00:31:24) TraceRefs (00:33:28) Advantages of refcounting (00:36:16) Disadvantages of refcounting (00:38:40) Reference cycles (00:40:39) Multithreading (00:41:25) When refcounting goes wrong (00:44:05) Freeing memory in Python doesn't return it to the OS (00:45:42) Leaks and cycles redux (00:50:29) Double free (00:53:05) Avoiding reference counting (00:54:59) Immortal objects (01:00:40) PART 2: WHAT'S GOING ON IN CPYTHON (01:02:43) New features (01:04:11) Assorted interesting changes (01:15:23) Performance (01:18:09) Free-threading changes galore (01:27:02) AsyncIO (01:34:25) Windows changes (01:36:45) Security (01:37:20) OUTRO

  4. 03/10/2024

    Episode 15: Core sprint at Meta

    Over 40 core developers spent a week in Bellevue WA putting finishing touches on Python 3.13, planning, prototyping, and implementing features for Python 3.14. We talked to half of them. We laughed, we cried. We were happy watching graphs go up, and sad watching them go down. It was intense. There was even cake, no joke! ## Timestamps (00:00:00) INTRO (00:02:05) PART 1: THE CAKE IS NOT A LIE (00:04:09) Interview with sprint organizer Itamar Oren (00:07:48) Surprise waffle machine (00:08:36) PART 2: DEVELOPERS IN THEIR OWN WORDS (00:08:47) Brandt Bucher (00:10:49) Tian Gao (00:12:31) Hugo van Kemenade (00:16:35) Thomas Wow-ters (00:24:08) Yury Selivanov (00:29:33) Mark Shannon (00:30:56) Raymond Hettinger (00:32:06) Russell Keith-Magee (00:33:18) Mariatta (00:41:41) Larry Hastings (00:46:07) Barry Warsaw (00:53:10) Jelle Zijlstra (00:56:20) Alex Waygood (00:57:39) Gregory P. Smith (01:04:08) Petr Viktorin (01:04:49) Emily Morehouse-Valcarcel (01:08:27) Interlude: Łukasz was right for once (01:09:28) Lysandros Nikolaou (01:17:38) Dino Viehland (01:23:22) Carl Meyer (01:24:29) Eric Smith (01:32:00) Eric Snow (01:41:46) Janitor 1 (01:50:01) Janitor 2 (01:53:03) OUTRO

  5. 10/06/2024

    Episode 12: WTF Python

    You think you know Python? We thought so, too. Join us for an episode of surprises. You might know some of those, but you sure don't know all of them. ## Outline (00:00:00) INTRO (00:02:22) Integer interning with a twist (00:10:58) Return in finally (00:15:32) all([[]]) (00:20:06) Lists, iterators and hashing shenanigans (00:27:08) hash(-1) (00:31:30) String interning (00:34:23) PR OF THE WEEK (00:34:56) asyncio REPL now uses pyrepl, too (00:44:06) PyOS_InputHook (00:51:56) WHAT'S GOING ON IN CPYTHON (00:52:05) New core developers! (00:55:10) 3.13 beta 2 & 3.12.4 released (00:56:04) Pablo's top 3 favorite pyrepl improvements in Beta 2 (00:59:50) PEP 667 implemented! (01:02:42) Tian Gao's improvements to pdb (01:06:31) Uncle Tim's crusade to make int(some_string) asymptotically faster (01:08:50) datetime now uses interpreter-local static types (01:09:55) PEP 749 enters the chat, paving the way to a PEP 649 future (01:11:35) os.fwalk, os.walk, shutil.rmtree now support arbitrary depth directory trees (01:14:13) Free-threading changes (01:22:15) OUTRO

  6. 28/05/2024

    Episode 11: Live from PyCon 2024

    Who says we can't do short episodes? Well, it was a challenge! But with the help of some gentle conference schedule pressure, here's our first sub-hour episode. We're discussing the language summit, answering audience questions, and behaving like serious professionals, as usual. ## Outline (00:00:00) INTRO (00:02:01) PEP 602 tweaks: 2 years of bug fix releases (00:02:45) CalVer for Python versions? (00:04:51) In Python there's this thing called the C API (00:08:51) More about PyREPL (00:12:17) Evolving pdb (00:14:49) Memhive (00:16:18) The boring 3.13 (00:18:16) Q&A (00:18:43) Fashion + favorite bug (00:22:12) What happens in 2100 with CalVer? (00:23:02) Subinterpreters or free-threading? (00:23:41) Where else to find information on current development? (00:25:40) Will distros provide free-threading builds? (00:26:23) Will the podcast run out of content? (00:28:37) OUTRO

  7. 03/05/2024

    Episode 10: The Interactive REPL

    Oof, no episode in April, huh? Yeah, we're getting close to Python 3.13 beta 1. PyCon US is also coming up real soon. Let's use this opportunity then to talk about a feature we're teaming up on: a better interactive interpreter! ## Outline (00:00:00)  INTRO (00:01:53)  PART 1: History of Terminals (00:03:20)  /dev/tty (00:04:51)  The first cool word (00:05:45)  Chrząszcz (00:06:20)  Control code characters in ASCII (00:11:54)  PART 2: Python REPL Today (00:12:34)  There is no REPL (00:15:28)  So what is there instead? (00:19:13)  readline (00:25:38)  Source in the REPL (00:31:13)  Implementing a REPL from scratch? Prepare to support arg: 5 (00:36:09)  PART 3: PR OF THE WEEK (00:37:09)  Introducing: Complaining Pablo (00:38:23)  Tests are always green if you skip them (00:39:57)  Getting dirty with escape sequences (00:41:28)  Typing finds bugs (00:42:29)  Shiny new features of the new REPL (00:45:55)  Contributing back to PyPy (00:48:10)  We still have two weeks, right? (00:49:59)  Is Python synthwave enough? (00:51:57)  Do we have a bug? (00:55:31)  What's lurking in pydoc? (00:59:38)  PART 4: WHAT'S HAPPENING IN CPYTHON? (01:02:39)  PEP 744: The JIT (01:06:05)  Incremental GC is now actually in (01:08:21)  Tier 2 interpreter updates (01:10:29)  Python supported on iOS with PEP 730 (01:13:11)  Better error messages for name shadowing (01:15:17)  Queue.shutdown() (01:17:14)  ctypes adopts heap types (01:18:26)  Free-threading updates (01:20:14)  Dataclass creation is faster (01:20:44)  OUTRO

  8. 14/03/2024

    Episode 9: Py Day with Emily Morehouse-Valcarcel

    Let's talk about the Steering Council, running a small consultancy business, the Walrus, and pet peeves with our special guest today! ## Outline (00:00:00)  INTRO (00:00:56)  PART 1: Emily Morehouse (00:02:15)  Running a small consultancy business (00:04:39)  What features of JS do you miss in Python? (00:05:50)  Łukasz outnumbered in a world of Steering Council members (00:06:12)  Upgrading to new Python versions (00:07:00)  It depends on who deployed the project (00:09:44)  Second term as a Steering Council member (00:11:33)  Barry, play some bass for us (00:13:04)  Let's hear a recent war story (00:15:17)  Is this progress bar even working? (00:17:40)  The Villain Origin Story (00:21:37)  Emily, The Bringer of Doom (00:22:37)  Consensus within the Steering Council (00:25:52)  Syntax changes in Python are rare, right? Right? (00:28:22)  On implementing PEP 572 (00:32:52)  How would PyCon 2020 in Pittsburgh feel? (00:34:18)  How can you be mad about the Walrus? (00:36:10)  Favorite parts of the standard library (00:38:10)  Is hacking on Python a good experience to newcomers? (00:40:26)  Emily's pet peeve about Python, take 1 (00:42:17)  Emily's favorite change in Python in recent years (00:44:34)  Emily's pet peeve about Python, take 2 (00:46:34)  Łukasz's pet peeve (00:48:25)  Surprise extra question (00:49:42)  At core.py we are professionals (00:51:00)  PART 2: PR of the Week (00:54:00)  CALL TO ACTION: Upgrade Python.org to Django 4! (00:56:22)  PART 3: What's Going On in CPython? (00:56:38)  Faster Python updates (01:00:10)  Free threading: GIL can be disabled but we're not done yet! (01:04:17)  New defaults for SSL context flags (01:05:39)  python -m asyncio and sys.__interactivehook__ (01:06:24)  Surprise question: what is sys.__interactivehook__ even doing? (01:08:11)  OUTRO

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About

We talk about Python internals, because we work on Python internals. We joke about stuff, because we’re jokers. Episodes between 60 and 90 minutes in length. We’ve done more than a few so far and it doesn’t seem like we’ll be stopping any time soon! Hi Loren!

Information

  • Creator
    Pablo Galindo and Łukasz Langa
  • Years Active
    2023 - 2026
  • Episodes
    31
  • Rating
    Clean
  • Copyright
    © Pablo Galindo and Łukasz Langa
  • Show Website
    core.py

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