Victor Stinner blog 3

In 2020, I created a new pythoncapi_compat project to add Python 3.10 support to C extensions without losing support for old Python versions. It supports Python 2.7-3.10 and PyPy 2.7-3.7. The project is made of two parts:

• pythoncapi_compat.h: Header file providing new C API …

This article is about changes that I made, with the help other developers, in the Python C API in Python 3.8, 3.9 and 3.10 to avoid accessing structures members: prepare the C API to make structures opaque. These changes are related to my PEP 620 "Hide implementation …

This article is about the work done in Python in 2019 and 2020 to better isolate subinterpreters. Static types are converted to heap types, extension modules are converted to use the new multiphase initialization API (PEP 489), caches, states, singletons and free lists are made per-interpreter, many bugs have been …

This article is the history of Python C API discussions over the last 4 years, and the creation of C API projects: pythoncapi website, pythoncapi_compat.h header file and HPy (new clean C API). More and more people are aware of issues caused by the C API and are working …

This article is about old reference leaks discovered or caused by the work on isolating subinterpreters: leaks in 6 different modules (gc, _weakref, _abc, _signal, _ast and _thread).

My previous article Daemon threads and the Python finalization in Python 3.2 and 3.3 introduces issues caused by daemon threads in the Python finalization and past changes to make them work.

This article is about bugfixes of the infamous GIL (Global Interpreter Lock) in Python 3.9, between …

This article is about a race condition in threading shutdown that I fixed in Python 3.9 in March 2019. I also forbid spawning daemon threads in subinterpreters to fix another related bug.

Drawing: #CoronaMaison by Julien Neel.

At exit, the Python finalization calls Python objects finalizers (the __del__() method) and deallocates memory. The daemon threads are a special kind of threads which continue to run during and after the Python finalization. They are causing race conditions and tricky bugs in the Python finalization.

This article covers bugs …

This article describes the discussion on the design of the development mode (-X dev) that I added to Python 3.7 and how it has been implemented.

The development mode enables runtime checks which are too expensive to be enabled by default. It can be enabled by python3 -X dev …