On 2021-11-19 23:44, Marco Sulla wrote:
On Fri, 19 Nov 2021 at 20:38, MRAB <pyt...@mrabarnett.plus.com> wrote:
On 2021-11-19 17:48, Marco Sulla wrote:
> I have a battery of tests done with pytest. My tests break with a
> segfault if I run them normally. If I run them using pytest -v, the
> segfault does not happen.
>
> What could cause this quantical phenomenon?
>
Are you testing an extension that you're compiling? That kind of problem
can occur if there's an uninitialised variable or incorrect reference
counting (Py_INCREF/Py_DECREF).
Ok, I know. But why can't it be reproduced if I do pytest -v? This way
I don't know which test fails.
Furthermore I noticed that if I remove the __pycache__ dir of tests,
pytest does not crash, until I re-ran it with the __pycache__ dir
present.
This way is very hard for me to understand what caused the segfault.
I'm starting to think pytest is not good for testing C extensions.
If there are too few Py_INCREF or too many Py_DECREF, it'll free the
object too soon, and whether or when that will cause a segfault will
depend on whatever other code is running. That's the nature of the
beast: it's unpredictable!
You could try running each of the tests in a loop to see which one
causes a segfault. (Trying several in a loop will let you narrow it down
more quickly.)
pytest et al. are good for testing behaviour, but not for narrowing down
segfaults.
--
https://mail.python.org/mailman/listinfo/python-list
