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Freethreading interpreter will attempt to import unsupported stable ABI extension modules #120901
Description
Bug report
Bug description:
Compile a stable ABI extension module with the filename "something.abi3.so" (or .pyd on Windows)
Run python -c "import something"
A freethreading build will attempt to import the extension module, even though it explicitly isn't compatible with the stable ABI. This (unsurprisingly) leads to a crash.
Tested on beta 3.13.0b2 (but a quick search didn't find relevant changes after that)
CPython versions tested on:
3.13
Operating systems tested on:
Linux
Activity
colesbury commentedon Jun 24, 2024
The
abi3.soor.pydsuffixes aren't enough to identify supported Python versions. For example, you can have an ABI 3.14+ library withabi3.soand Python 3.5 will load it and crash.colesbury commentedon Jun 27, 2024
I think we should probably refuse to load
something.abi3.soin the free-threaded build, but I don't think we can do that forsomething.pydon Windows (norsomething.soon Unix).@da-woods, can you provide more context on how you ran into this?
da-woods commentedon Jun 27, 2024
I didn't intend to propose this. I the sentence "(or .pyd on Windows)" was a bit ambiguous and I only meant ".abi3.pyd on Windows".
I was testing an in-place no-gil build of Cython and hadn't properly cleared up all the .so files before trying to test something else with free-threading Python. This is obviously something you're more likely to run into when doing ad-hoc development of extension modules rather than using pre-compiled wheels.
colesbury commentedon Jun 27, 2024
I don't think Windows uses
.abi3.pydas a suffix, just.pydfor both ABI 3 shared libraries and unversioned shared libraries.That makes sense. I think that's related to #121103, where the free-threaded and default builds both use the same
lib/python3.13directory (and I think we should change that).kumaraditya303 commentedon Nov 6, 2025
I think this is addressed by check added in #137957, @encukou?
encukou commentedon Nov 6, 2025
That checks will only print a better error message before the crash
PEP 803 (draft) adds some more: making
Py_mod_abimandatory in the future, and explicitly saying that it's the responsibility of users (and their tools) to not put incompatible extensions on PYTHONPATH.None of that is a fix, of course, but all three (and #121103) should help ad-hoc development :)
✨ feat(build): support free-threaded Python wheels (#307)