How many cores does your machine have, 10, 18? Your async Python code uses just one of them. That isn't a bug in asyncio. That's the design, and optimizing event loops to be faster by 20% doesn't change it. So Giovanni Barillari started over. Joe is the creator of Granian, the Rust-based server that powers Talk Python. His new project is TonIO, an async runtime written from scratch for free-threaded Python. Real threads, a handful of primitives instead of asyncio's pile of them, and it flat out refuses to start if the GIL is on. 
 
Episode sponsors 
 
<a href='https://talkpython.fm/sentry'>Sentry Error Monitoring, Code talkpython26</a>
<a href='https://talkpython.fm/devopsbook'>Python in Production</a>
<a href='https://talkpython.fm/training'>Talk Python Courses</a> 
 
<h2 class="links-heading mb-4">Links from the show</h2>
<div>Guest 
Giovanni Barillari: <a href="https://github.com/gi0baro?featured_on=talkpython" target="_blank" >github.com</a> 
 
Granian: <a href="https://github.com/emmett-framework/granian?featured_on=talkpython" target="_blank" >github.com</a> 
Hyper: <a href="https://github.com/hyperium/hyper?featured_on=talkpython" target="_blank" >github.com</a> 
Free threaded Python: <a href="https://docs.python.org/3/howto/free-threading-python.html#freethreading-python-howto" target="_blank" >docs.python.org</a> 
Sort of: <a href="https://labs.quansight.org/blog/free-threaded-one-year-recap?featured_on=talkpython" target="_blank" >labs.quansight.org</a> 
did a whole course: <a href="https://training.talkpython.fm/courses/python-concurrency-deep-dive" target="_blank" >training.talkpython.fm</a> 
uvloop: <a href="https://github.com/magicstack/uvloop?featured_on=talkpython" target="_blank" >github.com</a> 
rloop: <a href="https://github.com/gi0baro/rloop?featured_on=talkpython" target="_blank" >github.com</a> 
TonIO: <a href="https://github.com/gi0baro/tonio?featured_on=talkpython" target="_blank" >github.com</a> 
your EuroPython 2026 talk: <a href="https://www.youtube.com/watch?v=3GwyadhJZBQ&list=PLQHk3YPV3Dgk&index=4&t=753s" target="_blank" >www.youtube.com</a> 
Michael's Cutting Python Web App Memory Over 31% Article: <a href="https://mkennedy.codes/posts/cutting-python-web-app-memory-over-31-percent/?featured_on=talkpython" target="_blank" >mkennedy.codes</a> 
 
Watch this episode on YouTube: <a href="https://www.youtube.com/watch?v=lmG0ocDTsZo" target="_blank" >youtube.com</a> 
Episode #561 deep-dive: <a href="https://talkpython.fm/episodes/show/561/tonio-a-multi-threaded-async-runtime-for-python#takeaways-anchor" target="_blank" >talkpython.fm/561</a> 
Episode transcripts: <a href="https://talkpython.fm/episodes/transcript/561/tonio-a-multi-threaded-async-runtime-for-python" target="_blank" >talkpython.fm</a> 
 
Theme Song: Developer Rap 
🥁 Served in a Flask 🎸: <a href="https://talkpython.fm/flasksong" target="_blank" >talkpython.fm/flasksong</a> 
 
---== Don't be a stranger ==--- 
YouTube: <a href="https://talkpython.fm/youtube" target="_blank" > youtube.com/@talkpython</a> 
 
Bluesky: <a href="https://bsky.app/profile/talkpython.fm" target="_blank" >@talkpython.fm</a> 
Mastodon: <a href="https://fosstodon.org/web/@talkpython" target="_blank" > @talkpython@fosstodon.org</a> 
X.com: <a href="https://x.com/talkpython" target="_blank" > @talkpython</a> 
 
Michael on Bluesky: <a href="https://bsky.app/profile/mkennedy.codes?featured_on=talkpython" target="_blank" >@mkennedy.codes</a> 
Michael on Mastodon: <a href="https://fosstodon.org/web/@mkennedy" target="_blank" > @mkennedy@fosstodon.org</a> 
Michael on X.com: <a href="https://x.com/mkennedy?featured_on=talkpython" target="_blank" > @mkennedy</a> </div>

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