Crash with parallel testing

[saimn]

Description

Running tests in parallel with pytest fails:

❯ pytest -n 4                                             
===================================================================================== test session starts ======================================================================================
platform linux -- Python 3.12.2, pytest-8.1.1, pluggy-1.4.0

Running tests with Astropy version 6.1.dev557+ga74f314b6f.d20240312.
Running tests in astropy docs.

Date: 2024-03-12T23:06:03

Platform: Linux-6.7.9-arch1-1-x86_64-with-glibc2.39

Executable: /home/sconseil/.pyenv/versions/3.12.2/bin/python3.12

Full Python Version: 
3.12.2 (main, Mar 11 2024, 15:35:44) [GCC 13.2.1 20230801]

encodings: sys: utf-8, locale: UTF-8, filesystem: utf-8
byteorder: little
float info: dig: 15, mant_dig: 15

Package versions: 
Numpy: 1.26.4
Scipy: 1.12.0
Matplotlib: 3.8.3
h5py: 3.10.0
Pandas: 2.2.1
PyERFA: 2.0.1.1
Cython: 3.0.9
Scikit-image: 0.22.0
asdf-astropy: not available
pyarrow: not available

Using Astropy options: remote_data: none.

CI: undefined
ARCH_ON_CI: undefined
IS_CRON: undefined

rootdir: /home/sconseil/dev/astropy/astropy
configfile: pyproject.toml
testpaths: astropy, docs
plugins: anyio-4.3.0, filter-subpackage-0.2.0, astropy-0.11.0, arraydiff-0.6.1, cov-4.1.0, mock-3.12.0, remotedata-0.4.1, doctestplus-1.2.1, astropy-header-0.2.2, hypothesis-6.99.5, xdist-3.5.0
4 workers [28836 items]skipped                                                                                                                                                                 
collecting 0 items / 1 error / 4 skipped                                                                                                                                                       
============================================================================================ ERRORS ============================================================================================
_____________________________________________________________________________________ ERROR collecting gw2 _____________________________________________________________________________________
Different tests were collected between gw1 and gw2. The difference is:
--- gw1

+++ gw2

@@ -4389,16 +4389,16 @@

 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_ecsv_renamed_columns
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_ecsv_subclass_partial_info
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_ecsv_mutlirow
-astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_complete_info[ascii.html-False-True]
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_complete_info[ascii.latex-False-True]
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_complete_info[latex-False-True]
+astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_complete_info[ascii.html-False-True]
+astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_complete_info[json-True-True]
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_complete_info[ascii.ecsv-True-True]
-astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_complete_info[json-True-True]
-astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_from_subclass_complete_info[ascii.html-False-True]
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_from_subclass_complete_info[ascii.latex-False-True]
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_from_subclass_complete_info[latex-False-True]
+astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_from_subclass_complete_info[ascii.html-False-True]
+astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_from_subclass_complete_info[json-True-True]
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_from_subclass_complete_info[ascii.ecsv-True-True]
-astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_readwrite_from_subclass_complete_info[json-True-True]
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_meta_on_class
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_meta_on_instance
 astropy/cosmology/flrw/tests/test_base.py::TestFLRW::test_meta_mutable
@@ -4489,126 +4489,126 @@

... (and many many more)

Seems related to cosmology (cc @nstarman) and similar to pytest-dev/pytest-xdist#432 (thanks @pllim).

Expected behavior

No response

How to Reproduce

1. Get package from '...'
2. Then run '...'
3. An error occurs.

# Put your Python code snippet here.

Versions

import platform; print(platform.platform())
import sys; print("Python", sys.version)
import astropy; print("astropy", astropy.__version__)
import numpy; print("Numpy", numpy.__version__)
import erfa; print("pyerfa", erfa.__version__)
try:
    import scipy
    print("Scipy", scipy.__version__)
except ImportError:
    print("Scipy not installed")
try:
    import matplotlib
    print("Matplotlib", matplotlib.__version__)
except ImportError:
    print("Matplotlib not installed")

# Copy the result here