core.py

Inside of you there are two stacks. Actually, there’s three. The system-level call stack, the CPython call stack, and the interpreter’s evaluation stack. What is all that about? Today we’ll talk about how synchronous Python function calls work. Async stuff comes next time!## TimestampsHere you go — all square brackets changed to parentheses:(00:00:00) INTRO(00:02:28) PART 1: CALLING THINGS(00:04:19) The Lawful Good Language(00:13:18) Why is there a call stack?(00:19:45) Python functions are not tied to the system call stack(00:23:22) What's in a Python frame?(00:23:35) Execution book-keeping data(00:24:21) Locals(00:27:35) The interpreter evaluation stack(00:28:34) What are register-based interpreters?(00:36:33) Interpretation using the evaluation stack(00:42:46) Executing a function(00:45:37) How do exceptions fit into the execution model?(01:05:51) PART 2: PR OF THE WEEK(01:15:48) PART 3: DONATE.PYTHON.ORG(01:17:21) PART 4: WHAT'S GOING ON IN CPYTHON(01:27:59) Free threading changes(01:38:16) Performance(01:51:08) Bugfixes(02:04:03) OUTRO

More interviews from the core sprint! This time we have: Greg P. Smith, Thomas Wouters, Paul Ganssle, Pradyun Gedam, Carol Willing, Guido van Rossum, Brett Cannon, Erlend Aasland, Tal Einat, Lysandros Nikolaou, Yury Selivanov, and Diego Russo -- the organizer himself.## Timestamps(00:00:00) INTRO(00:01:51) Greg P. Smith(00:07:57) Thomas Wouters(00:16:33) Paul Ganssle(00:28:28) Pradyun Gedam(00:34:02) Carol Willing(00:43:32) Guido van Rossum(00:55:39) Brett Cannon(01:10:01) Erlend Aasland(01:14:05) Tal Einat(01:22:21) Lysandros Nikolaou(01:30:40) Yury Selivanov(01:45:08) Diego Russo(01:58:27) What did the hosts do?(02:17:18) OUTRO

What? What do you mean this two-and-a-half hour episode is PART 1? Well, there were fifty people at the sprint in September. We interviewed thirty of them. In Part 1 you can hear from 18 of them: Ken Jin, Alex Waygood, Russell Keith-Magee, Sam Gross, Steve Dower, Dino Viehland, Petr Viktorin, Peter Bierma, Eric V. Smith, Hugo van Kemenade, Savannah Bailey, Eric Snow, Brandt Bucher, Antonio Cuni, Larry Hastings, Hood Chatham, Victor Stinner, and Mark Shannon.## Timestamps(00:00:00) INTRO(00:02:43) Ken Jin(00:05:28) Alex Waygood(00:08:21) Russell Keith-Magee(00:17:32) Sam Gross(00:23:25) Steve Dower(00:26:17) Dino Viehland(00:36:02) Petr Viktorin(00:40:59) Peter Bierma(00:44:24) Eric V. Smith(00:55:25) Hugo van Kemenade(00:59:39) Savannah Bailey(01:08:53) Eric Snow(01:22:02) Brandt Bucher(01:38:53) Antonio Cuni(01:48:23) Larry Hastings(02:07:54) Hood Chatham(02:12:11) Victor Stinner(02:16:23) Mark Shannon(02:22:44) OUTRO

What if some rejected PEPs were actually accepted? How would Python look today? Let's go through 10 PEPs from the past and imagine an alternative future for the language!## Timestamps(00:00:00) INTRO(00:01:00) PART 1: What if rejected PEPs were accepted?(00:02:15) PEP 638: Syntactic Macros(00:13:53) PEP 505: None-aware operators(00:37:12) PEP 671: Late-bound function argument defaults(00:44:40) PEP 335: Overloadable Boolean Operators(00:50:53) PEP 3136: Labeled break and continue(00:52:49) PEP 463: Exception-catching expressions(01:00:58) PEP 511: API for code transformers(01:06:30) PEP 340: Anonymous block statements(01:10:30) PEP 276 and PEP 284: Alternative integer iteration(01:17:12) The do: while: loop(01:19:50) The final boss of Python syntax feature requests(01:25:33) PART 2: PR OF THE WEEK(01:36:17) Raw f-string format fixes(01:38:44) PART 3: WHAT'S GOING ON IN CPYTHON(01:40:55) Python 3.14 RC2 and Python 3.13.7(01:43:20) Welcome to the core team, Emma(01:43:50) Welcome to the release team, Savannah(01:45:56) Free threading changes(01:47:49) Perf improvements(01:52:00) New features(01:57:20) Bugfixes(01:59:15) OUTRO

Python 3.14? That's old news. Let's talk about the first big feature of Python 3.15 -- a built-in sampling profiler for Linux, macOS, and Windows. We also cover improvements in perf support, discuss memory.python.org, and as usual, recent changes in the codebase.## Timestamps(00:00:00) INTRO(00:02:43) PART 1: THE SAMPLING PROFILER(00:05:07) Built-in profile is bad, long live cProfile(00:10:54) Out-of-process profiling(00:12:18) Shortcuts Compromise Accuracy, Leading Eventually to Numerous Errors(00:16:07) Selfish Łukasz vs benevolent Pablo(00:23:11) How does a sampling profiler even work?(00:30:42) One meeellion huuurtzzz(00:32:40) Free threading makes it extra spicy(00:41:26) AsyncIO makes it even spicier(00:49:49) You made this? I made this(00:54:06) What if the profiled process changes during sampling?(00:57:33) Coming in October 2026(01:04:30) PART 2: PR OF THE WEEEEEEK(01:14:14) memory.python.org launched(01:23:15) PART 3: WHAT'S GOING ON IN CPYTHON(01:26:45) Performance updates(01:30:24) Features & Curiosities(01:41:45) OUTRO