Improving NumPy Performance on Free-Threaded Python

2026-08-14

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What bottlenecks were preventing NumPy from scaling on free-threaded Python? Christopher Trudeau is back on the show this week with another batch of PyCoder’s Weekly articles and projects. Christopher shares a recent article on the work done in NumPy to make multi-threaded workloads scale on the free-threaded build of CPython. It covers how removing the Global Interpreter Lock (GIL) is not enough on its own and how profiling revealed hidden bottlenecks in NumPy and CPython. We also share other articles and projects from the Python community, i...

What bottlenecks were preventing NumPy from scaling on free-threaded Python? Christopher Trudeau is back on the show this week with another batch of PyCoder’s Weekly articles and projects.

Christopher shares a recent article on the work done in NumPy to make multi-threaded workloads scale on the free-threaded build of CPython. It covers how removing the Global Interpreter Lock (GIL) is not enough on its own and how profiling revealed hidden bottlenecks in NumPy and CPython.

We also share other articles and projects from the Python community, including recent releases, a pair of announcements from PyPI, a tool for crawling your Django project, SIMD in pure Python, managing wildcard imports, a publication-quality Python Data Visualization library, and a tool to review your Django schema.

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Topics:

00:00:00 – Introduction
00:02:26 – Python 3.15.0 candidate 1 is here!
00:02:47 – Python 3.14.7 and 3.13.15 are now available!
00:03:00 – Django 6.1 released
00:03:39 – Planned Updates to the PyPI User Interface
00:04:13 – PyPI Releases Now Reject New Files After 14 Days
00:05:07 – PEP 837 – Extensible JSON serialization
00:06:20 – PEP 842: Module Exports
00:07:51 – Introducing django-crawl
00:12:02 – SIMD in Pure Python
00:18:29 – Managing Imports With Python’s __all__
00:29:34 – Spotlight: Modern Object-Oriented Python Book
00:30:53 – Scaling NumPy on Free-Threaded Python
00:37:53 – cnsplots: Python Data Visualization for Complex Datasets
00:42:19 – django-orm-lens: Django Schema Review
00:45:14 – Thanks and goodbye

News:

Python 3.15.0 candidate 1 is here! - Python Insider
Python 3.14.7 and 3.13.15 are now available! - Python Insider
Django 6.1 released - Weblog - Django
Planned Updates to the PyPI User Interface – Over the next few months a new user interface will be rolled out for the Python packaging website, PyPI. The rollout will be done in phases to make sure it is rock solid and to get community feedback. This post talks about the history of PyPI’s UI and what is changing.
PyPI Releases Now Reject New Files After 14 Days – “The Python Package Index (PyPI) now rejects new files being uploaded to releases that are older than 14 days. This restriction was put in place to prevent old and long-stable releases from being poisoned”
PEP 837 – Extensible JSON serialization
PEP 842: Module Exports

Show Links:

Introducing django-crawl – During a recent site migration, Adam used the Django test harness to crawl his site looking for missing security headers. In the process he uncovered seven other bugs for a project that had 100% code coverage. He has consolidated the crawling technique for testing into a library: django-crawl.
SIMD in Pure Python – SIMD is Single Instruction, Multiple Data, an approach that does calculations with vectors of data sets. Python doesn’t support it natively, but libraries like NumPy allow you to code this way.
Thoughts on “SIMD in Pure Python” - purplesyringa’s blog
Managing Imports With Python’s __all__ – Learn how Python’s dunder all variable controls wildcard imports and shapes the public API your packages and modules expose.
Scaling NumPy on Free-Threaded Python – A recap on the work done in NumPy and CPython to make multi-threaded NumPy workloads scale on the free-threaded build of CPython.

Projects: