Using pytest-xdist causes AttributeError: module '__main__' has no attribute '__file__'

Question

I am trying to use pytest-xdist to run my tests faster by running on multiple CPUs. However, when I switch to using multiple CPUs the tests don't run because there is an error when collecting the tests.

More specifically, the error is

AttributeError: module '__main__' has no attribute '__file__'

This is because the scripts being tested import a logging module I wrote. The logging module uses

__main__.__file__

to determine the name of the main application for purposes of adding it to the log output filename.

I can't seem to figure out what pytest is doing differently in multiple CPU mode than in single CPU mode.

So when I execute my tests as

python3 -m pytest

everything runs just fine, but once I switch to

python3 -m pytest -n 4

I get these errors:

____________________ ERROR collecting ***.py
***/logging/log_setup.py:21: in <module>
    app_name = os.path.basename(__main__.__file__)[:-3]
E   AttributeError: module '__main__' has no attribute '__file__'

The same problem occurs when I try to execute using the Python subprocess method:

python3 -m pytest -d --tx 3*popen//python=python3

EDIT: I am side stepping the issue for now with the following code in my logging module:

if hasattr(__main__, '__file__'):
    app_name = os.path.basename(__main__.__file__)[:-3]
else:
    app_name = 'unknown_app_name'

Now pytest with multiple CPUs works fine for me.