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GeezerVison is showing github.com — GH-139109: Partial reworking of JIT data structures by markshannon · Pull Request #144105 · python/cpython

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@markshannon

@markshannon markshannon commented Jan 21, 2026 •
edited by bedevere-app Bot
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  • Halve size of buffers by reusing combined trace + optimizer buffers for TOS caching
  • Add simple buffer struct for more maintainable handling of buffers
  • Decouple JIT structs from threadstate struct
  • Ensure terminator is correctly added to trace, when optimizer gives up.

This is the first PR of a series to reducing coupling, particularly hidden coupling, in the tracer.
This is a bit of a mixed assortment of small changes to prepare for more significant changes later.
It also fixes a bug that was exposed by the refactoring.

  • Issue: Trace recording JIT #139109

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@markshannon
Partial reworking of JIT data structures
42677ab 
* Halve size of buffers by reusing combined trace + optimizer buffers for TOS caching
* Add simple buffer struct for more maintainable handling of buffers
* Decouple JIT structs from thread state struct
* Ensure terminator is added to trace, when optimizer gives up
@markshannon
markshannon requested review from Fidget-Spinner, ZeroIntensity, ericsnowcurrently, savannahostrowski and tomasr8 as code owners January 21, 2026 11:54
@bedevere-app bedevere-app Bot mentioned this pull request Jan 21, 2026
Trace recording JIT #139109
Open
@bedevere-app bedevere-app Bot added the awaiting core review label Jan 21, 2026
@markshannon markshannon added the skip news label Jan 21, 2026
Fidget-Spinner
Fidget-Spinner approved these changes Jan 21, 2026
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Just 2 nits, please address them and merge.

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Comment thread Include/internal/pycore_optimizer.h Resolved

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Comment thread Include/internal/pycore_optimizer.h Resolved

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@bedevere-app bedevere-app Bot added awaiting merge and removed awaiting core review labels Jan 21, 2026
@markshannon
Avoid implicit cast
4f5f3e7
@markshannon
markshannon merged commit d77aaa7 into python:main Jan 22, 2026
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@bedevere-app bedevere-app Bot removed the awaiting merge label Jan 22, 2026
thunder-coding pushed a commit to thunder-coding/cpython that referenced this pull request Feb 15, 2026
@markshannon @thunder-coding
pythonGH-139109: Partial reworking of JIT data structures (pythonGH-1…
8bcb200 
…44105)

* Halve size of buffers by reusing combined trace + optimizer buffers for TOS caching
* Add simple buffer struct for more maintainable handling of buffers
* Decouple JIT structs from thread state struct
* Ensure terminator is added to trace, when optimizer gives up
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@Fidget-Spinner Fidget-Spinner Fidget-Spinner approved these changes
@ericsnowcurrently ericsnowcurrently Awaiting requested review from ericsnowcurrently ericsnowcurrently is a code owner
@ZeroIntensity ZeroIntensity Awaiting requested review from ZeroIntensity ZeroIntensity is a code owner
@tomasr8 tomasr8 Awaiting requested review from tomasr8 tomasr8 is a code owner
@savannahostrowski savannahostrowski Awaiting requested review from savannahostrowski

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@markshannon @Fidget-Spinner
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