Re: [OE-core] [RFC][PATCH 00/14] Support Python freethreading

["Böszörményi Zoltán" <zboszor@gmail.com>]

2026. 03. 25. 14:17 keltezéssel, Bruce Ashfield írta:
>
>
> On Wed, Mar 25, 2026 at 9:13 AM Böszörményi Zoltán <zboszor@gmail.com> wrote:
>
>     2026. 03. 25. 14:01 keltezéssel, Bruce Ashfield írta:
>     >
>     >
>     > On Wed, Mar 25, 2026 at 7:31 AM Zoltan Boszormenyi via lists.openembedded.org
>     <http://lists.openembedded.org>
>     > <http://lists.openembedded.org> <zboszor=gmail.com@lists.openembedded.org> wrote:
>     >
>     >     This patchset allows turning on Python freethreading by using
>     >     a new DISTRO_FEATURES setting:
>     >
>     >     DISTRO_FEATURES += "python_freethreading"
>     >
>     >     and optionally:
>     >
>     >     DISTRO_FEATURES_NATIVE += "python_freethreading"
>     >
>     >     The change to python3-dir.bbclass is crucial, as all python module
>     >     build helper classes rely on it.
>     >
>     >     I also added native variants of some settings because another
>     >     series against meta-openembedded is needed to complete this one.
>     >     In that, the change to the fontforge recipe relies on the native
>     >     setting for setting BUILD_LDFLAGS.
>     >
>     >
>     > Looking at those other patches in the series, they don't seem to
>     > be conditional on the distro feature.
>     >
>     > Are those changes valid for a build with and without freethreading ?
>
>     Yes!
>
>     The main change is in python3-dir.bbclass, and the recipe tweaks
>     are just adaptations to the fact that only ${PYTHON_DIR} is needed,
>     not ${PYTHON_DIR}${PYTHON_ABI} from that point.
>
>     I was thinking that the introductory mail stressed this enough.
>
>
> Obviously not :)

Obviously. :)

> I didn't get that impression at all from reading the introductory
> message or looking at the patches themselves.
>
> You have the overview knowledge of the feature, why it is
> useful, how it impacts existing recipes, how the migration would
> work, what is the compatibility, etc.

I think the Python 3.14 release notes has enough details.
See also https://www.phoronix.com/news/Python-3.14

With the two series I sent, only a single recipe is left (cmpi-bindings)
in openembedded-core and meta-openembedded that uses
the PYTHON_ABI setting explicitly.

Migration (of python scripts) should not be a problem.
If it worked with 3.14 as is, it works with freethreading enabled.

Compatibility is poor for a lot of modules, that clearly spell this out
in their pyproject.toml or PKG-INFO:

     "Programming Language :: Python :: Free Threading :: 1 - Unstable"

or something not quite production level support.
It's still experimental for 3rd party modules, despite being officially
supported for the interpreter and built-in modules in 3.14.

This is the reason this was an RFC series.

Anyway, the reason I was experimenting with this was that
with heavily threaded python code, an import storm can cause
a crash in 3.12.11 or the manually updated 3.13.12 in Yocto 5.3 in
importlib._bootstrap according to the backtrace.

I would like to see if Python 3.14 (with and without freethreading)
fixes such crashes.

> The patch reader doesn't, so that all needs to be clearly
> supplied.

Maybe next time for v2 after I have a complete image
successfully built with freethreading enabled.

>
> Bruce
>
>
>
>     FWIW, less than 30 recipes was spelling the latter out in
>     openembedded-core and meta-openembedded combined.
>
>     > That's the type of information, along with the benefits of enabling
>     > this would be information expected in a 0/N introductory patch.
>     >
>     > Cheers,
>     >
>     > Bruce
>     >
>     >
>     >     All of the changes included here were successfully build tested,
>     >     except for the gdb-cross-canadian change. That one failed, but
>     >     it's included for completeness.
>     >
>     >     Quite a few of python modules were build tested for native and
>     >     target builds, including python3-pytorch from my meta-python-ai
>     >     with reduced RDEPENDS because e.g. python3-onnx there failed
>     >     to build with freethreading enabled.
>     >
>     >     All in all, this series at least allows to get things going.
>     >     Though maybe not for Yocto 6.0, as it's quite late.
>     >
>     >     Best regards,
>     >     Zoltán Böszörményi
>     >
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> -- 
> - Thou shalt not follow the NULL pointer, for chaos and madness await thee at its end
> - "Use the force Harry" - Gandalf, Star Trek II
>