#565: Tachyon, Python 3.15's Built-in Sampling Profiler

Do you know what's actually slow in your Python app? Or are you guessing? Until now, profiling Python meant a tracing profiler that made your code 2 to 3 times slower. Or a third-party tool that broke with every new release. Python 3.15 fixes that. It ships Tachyon, a sampling profiler built into the standard library. It attaches to live production apps with almost zero overhead. My guests are Pablo Galindo Salgado, CPython core developer and Steering Council member, and László Kiss Kollár from Bloomberg's Python infrastructure team. Their first prototype ran at two samples a second. Now it does over a million hz. And it lands in Python 3.15 this October.

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Links from the show

Guests
László Kiss Kollár: linkedin.com
Pablo Galindo Salgado

3.11: talkpython.fm
Memray: talkpython.fm
PyStack: talkpython.fm
profile and cProfile: docs.python.org
py-spy: github.com
Austin: github.com
PEP 799: peps.python.org
PEP 768: peps.python.org
PyCon US 2026 talk: us.pycon.org
The docs: docs.python.org
Backport to 3.14: github.com

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Episode #565 deep-dive: talkpython.fm/565
Episode transcripts: talkpython.fm

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