doctest memory increasing

Describe what maintenance you would like added.

The current usage of doctest has increasing memory. #2496 has increased the number of doctests to the point that the CI runs out of memory. Locally, the memory increases >10 GB on some commit refs. Currently, none of the Plotters are being closed, and thus memory increases each time a plot is made. Confirmation of this is below. However, normal doctest does not allow for convenient use of teardown code. And we’d have to add pyvista.all_close() to every doctest.

pytest-doctestplus can fix this issue while providing more flexible doctesting for our uses. It allows using pytest fixtures, which enables for clean teardown code to be run after each doctest without adding fluff to each doctest.

When using pytest-doctestplus with the fixture below eliminates the memory buildup seen, which confirms that the plotters aren’t closing properly today.

@pytest.fixture(autouse=True)
def autoclose_plotters():
    yield
    pyvista.close_all()

Downsides

• Potentially breaks usage with base doctest. The option flag NUMBER is not supported, but FLOAT_CMP can be used. FLOAT_CMP rounds to nearest whereas NUMBER rounds down. Switching would prevent using normal doctest. This could potentially be avoided by using ELLIPSES instead, but it might have unintended edge cases.
• I’m not sure if this impacts check_doctest_names

[akaszynski]

@MatthewFlamm, I’m finding this works on my end without using pytest-doctestplus

import pyvista

import pytest

@pytest.fixture(autouse=True)
def autoclose_plotters():
    yield
    pyvista.close_all()

[adeak]

I’m not sure if this impacts check_doctest_names

check_doctest_names only uses stdlib doctest as a parser, and it only checks for exceptions being raised in doctests (with the assumption that proper doctesting checks validity of results). So it should be of no concern.