The Megahertz

core.py

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