Memory leak with ndarray as function arg in Cython

[ArtificialQualia]

When using an ndarray as an arg to a cdef function, and that ndarray is not used in the function, that object is never properly garbage collected and causes a memory leak.

If the ndarray is used in the function, it is collected properly.

Reproducing code example:

memleak.pyx

import numpy as np
cimport numpy as cnp
from numpy cimport ndarray
cnp.import_array()

cdef inline void caller():
    cdef:
        ndarray[int] x
    x = np.asarray(range(10000))
    dont_use_x(x)

cdef inline void dont_use_x(ndarray[int] x):
    pass

while True:
    caller()

setup.py:

from distutils.core import setup
from Cython.Build import cythonize
import numpy

setup(
    ext_modules = cythonize("memleak.pyx"),
    include_dirs=[numpy.get_include()]
)

to run:

python setup.py build_ext --inplace
python
import memleak

Numpy/Python version information:

1.16.2 3.7.1 (default, Dec 10 2018, 22:54:23) [MSC v.1915 64 bit (AMD64)]

[mattip]

This seems like a cython issue. Can you raise it there?

[seberg]

Closing, since it is a cython issue as mentioned (and that issue has been created).