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[Python] Editing a .pyx requires building extensions twice for the change to take effect #50702
Description
Describe the bug, including details regarding any error messages, version, and platform.
I've found a couple of places where I am modifying some Cython code on a .pyx file and when I rebuild the expected changes are not in effect, if I rebuild a second time the changes take effect.
If I take a look after a build:
$ # edit python/pyarrow/_flight.pyx
$ python -m pip install -C cmake.build-type=Debug -C build.verbose=true --no-deps --no-build-isolation -vv --config-settings=build-dir=build -e .
$ ls -lrta pyarrow/_flight.pyx build/_flight.cpp build/debug/_flight.cpython-313-x86_64-linux-gnu.so
-rwxrwxr-x 1 raulcd raulcd 6847840 Jul 29 09:59 build/debug/_flight.cpython-313-x86_64-linux-gnu.so
-rw-rw-r-- 1 raulcd raulcd 114900 Jul 29 10:02 pyarrow/_flight.pyx
-rw-rw-r-- 1 raulcd raulcd 4288269 Jul 29 10:02 build/_flight.cppThe cpp file was re-generated but the _flight.cpython-313-x86_64-linux-gnu.so was not, it predates the build time and the pyx change.
Component(s)
Python
Activity
[-][Python] Editing a .pyx requires running build_ext twice for the change to take effect[/-][+][Python] Editing a .pyx requires building extensions twice for the change to take effect[/+]pratyushadk commentedon Jul 29, 2026
hey, this issue looks interesting, can i give it a try?
raulcd commentedon Jul 29, 2026
sure, feel free to try.
GH-50702: [Python] Fix .pyx changes requiring two builds to take effe…
pitrou commentedon Jul 30, 2026
Issue resolved by pull request 50719
#50719