- Developers
- Learn about specific Python 3.12 features Meta contributed, like custom JITs and type system enhancements, to optimize your code.
- Business
- Understand how Meta influences open-source tools to improve performance and efficiency for large-scale applications.
This episode features Meta engineers discussing their direct contributions to a major programming language update, offering technical depth.
59: Meta ❤️ Python 3.12
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From Subvolts
Summary and analysis by Subvolts editorial, AI-assisted.
Meta Tech Podcast episode 59 features Carl and Itamar discussing their contributions to Python 3.12. They cover new features like custom JIT hooks (Cinder), Immortal Objects, type system improvements, and faster comprehensions. The conversation also touches on the process of contributing to open-source projects and engaging with the Python community. The episode highlights Meta's significant role in advancing the Python language.
Meta engineers discuss recent updates to Python, the programming language many websites and apps use. They explain new features they helped build, like ways to make programs run faster and handle data more efficiently. This matters because these improvements can make the software we use daily quicker and more reliable.
This episode is for developers interested in Python's evolution and Meta's role in it. It offers insights into how Meta influences core programming languages, which is relevant as frontier labs often optimize tools for their specific needs. Understanding these contributions helps gauge the direction of open-source development and the practical applications of advanced features like custom JITs, potentially impacting performance for large-scale applications.
- HostPascal Harris
- GuestCarlMeta
- GuestItamarMeta
- Episode Title: 59: Meta ❤️ Python 3.12
- Show: Meta Tech Podcast
- Length: 38 minutes
- Guest Contributions: Custom JITs (Cinder), Immortal Objects, type system improvements, faster comprehensions in Python 3.12
- Meta Careers Link: https://www.metacareers.com/
For the second time in just a few months, we are talking Python on the Meta Tech Podcast. Python 3.12 features a whole range of new features, many of which were contributed by Meta. Carl and Itamar join Pascal to talk about their contributions to the latest release, including new hooks that allow for custom JITs like Cinder, Immortal Objects, improvements to the type system, faster comprehensions and much more. In their discussion, they talk not just about how and why those features were built but also the process of upstreaming and engaging with the community.
Got feedback? Send it to us on Threads (https://threads.net/@metatechpod), Twitter (https://twitter.com/metatechpod), Instagram (https://instagram.com/metatechpod) and don't forget to follow our host @passy (https://twitter.com/passy, https://mastodon.social/@passy, and https://threads.net/@passy_). Fancy working with us? Check out https://www.metacareers.com/.
Links
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"Lazy is the new fast: How Lazy Imports and Cinder accelerate machine learning at Meta" - https://engineering.fb.com/2024/01/18/developer-tools/lazy-imports-cinder-machine-learning-meta/
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"How Meta built the infrastructure for Threads" - https://engineering.fb.com/2023/12/19/core-infra/how-meta-built-the-infrastructure-for-threads/
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Cinder on GitHub - https://github.com/facebookincubator/cinder
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"Meta contributes new features to Python 3.12" - https://engineering.fb.com/2023/10/05/developer-tools/python-312-meta-new-features/
Timestamps
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Intro 0:06
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Carl Intro 2:09
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Itamar Intro 3:27
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Teams and Missions 5:10
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Python 3
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Faster Coroutines 8:57
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Code Watchers and JIT Hooks 12:10
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When to upstream 13:53
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How to upstream to CPython 16:19
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History of Cinder 21:35
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Why not upstream Cinder? 25:48
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Cinder hooks in CPython 29:34
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Free Threading 34:10
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Outro 37:08
- JIT
- Itamar
- Just-In-Time compiler, a technology that speeds up program execution by compiling code as it runs.
- Cinder
- Itamar
- A specific type of JIT developed by Meta to improve Python performance.
- Immortal Objects
- Itamar
- A feature that allows certain objects in Python to persist longer, potentially improving efficiency.
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WithJoseph, Subasree
Questions people ask
- What did Meta contribute to Python 3.12?
- Meta engineers contributed several features, including hooks for custom JITs like Cinder, Immortal Objects, type system enhancements, and faster comprehensions.
- What is Cinder?
- Cinder is a custom JIT (Just-In-Time compiler) that Meta developed, and its integration is discussed in the context of Python 3.12's new features.
Page generated Oct 19, 2026. Summaries are Subvolts' own; the audio, artwork and notes belong to Meta.

