EuroSciPy 2026

Unravelling the mystery of free threading for scientific computing
2026-07-20 , Room 1.38 (Ground Floor, Turing)

Python’s Global Interpreter Lock (GIL) has long been a barrier for scientific computing, limiting the ability to fully utilise multi-core hardware and scale parallel workloads. With the introduction of free-threaded Python (PEP 703), this constraint is finally being lifted. Several core scientific Python packages (including NumPy, SciPy, and pandas) have already begun transitioning to support users who wish to use free-threading, paving the way for improved performance and concurrency for the broader ecosystem. This talk will explore what free-threading means for the scientific Python community, discuss the technical challenges in adopting this new paradigm, and highlight the practical impact it can have for users and maintainers. Attendees will receive actionable guidance for leveraging free-threading in their projects, including insights into the transition process and lessons learned from early adopters.


Target Audience

  • Python users in scientific computing (researchers, engineers, data scientists)
  • Open source package maintainers and contributors considering adopting free threading
    *Developers interested in Python performance and concurrency

What Attendees Will Learn

  • How free-threaded Python (PEP 703) changes concurrency and impacts scientific workloads
  • Which major packages currently support free-threading and latest updates
  • Practical tips and best practices for adopting free-threading in projects
    *Tools and resources to help transition codebases for the new paradigm

Outline:

1. Introduction: Why Free Threading Matters for Scientific Python (5 min)
* The GIL’s impact on scientific computing and parallel workloads

2. What Is Free-Threaded Python? (5 min)
* Overview of PEP 703 and Python 3.14t
* Difference between multi processing and threading

3. How is the ecosystem adapting? (10 min)
* Status update: which packages currently support free-threading (NumPy, SciPy, pandas, etc.)
* Early experiences from package developers and the community
* Share data on performance gains from transition to free threading
* Note to reviewer: this work is ongoing, so will have more detail to include here over the next few months

5. Lessons Learned and Best Practices (10 min)
* Practical tips for users: how to take advantage of free-threading in your code
* Share some case studies from OSS projects that have begun adopting FTP, describe technical hurdles faced
* Some tools / resources that can help you with the transition


Expected audience expertise: Domain: some Expected audience expertise: Python: expert Your relationship with the presented work/project:

Abby is a Developer Advocate at Meta focused on supporting the Python Open Source community. She has worn a bunch of hats over the years - software developer, developer advocate, product manager, and people manager - but a consistent thread has been her passion for making technology approachable for all.