Memory leak with vector of memoryviews

main.py

import numpy as np
import resource

import metric


def test_memory_leak():
    NB_LOOPS = 20
    NB_LINES = 10000
    NB_POINTS = 100

    lines = [np.empty((NB_POINTS, 3), dtype="float32")] * NB_LINES

    # Test fix
    ram_usages = np.zeros(NB_LOOPS)
    for i in range(NB_LOOPS):
        metric.fct_with_fix(lines)
        ram_usages[i] = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss

    print (["{0:.2f}Mo".format(ram/1024.) for ram in np.diff(ram_usages)])

    # Exposing memory leak
    ram_usages = np.zeros(NB_LOOPS)
    for i in range(NB_LOOPS):
        metric.fct_with_leaks(lines)
        ram_usages[i] = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss

    print (["{0:.2f}Mo".format(ram/1024.) for ram in np.diff(ram_usages)])

test_memory_leak()

metric.pyx

from libcpp.vector cimport vector

ctypedef float[:,:] Line
ctypedef vector[Line] Lines

cdef extern from *:
    void __PYX_XDEC_MEMVIEW(Line* memslice, int have_gil)


cpdef fct_with_leaks(Lines lines):
    pass

cpdef fct_with_fix(Lines lines):
    for i in range(lines.size()):
        __PYX_XDEC_MEMVIEW(&lines[i], 1)

setup.py

# -- setup.py --
import numpy as np

from setuptools import setup
from Cython.Distutils import build_ext
from numpy.distutils.extension import Extension

setup(
    cmdclass={'build_ext': build_ext},
    ext_modules=[Extension("metric",
                           ["metric.pyx"],
                           language='c++',
                           include_dirs=[np.get_include()])
                 ]
)