leaked share_memory

[JXQI]

when I run this code:
`
lobe_labe_map = snp.from_array(lobe_labe_map)
lesion_mask = snp.from_array(lesion_mask)
pixel_array = snp.from_array(pixel_array)
spacing = snp.from_array(spacing)

with Pool(5) as p:
func = partial(map_function, lobe_labe_map, pixel_array, spacing, is_pnmonia_flag)
res = p.map_async(func,KEYS.values())

lobe_labe_map.close()
lesion_mask.close()
pixel_array.close()
spacing.close()
lobe_labe_map.unlink()
lesion_mask.unlink()
pixel_array.unlink()
spacing.unlink()
`
the func just use shared numpy, do not change anything.

that happen:

/usr/local/lib/python3.7/multiprocessing/resource_tracker.py:218: UserWarning: resource_tracker: There appear to be 3 leaked shared_memory objects to clean up at shutdown
(len(rtype_cache), rtype))
/usr/local/lib/python3.7/multiprocessing/resource_tracker.py:229: UserWarning: resource_tracker: '//psm_7dd83f76': [Errno 2] No such file or directory: '//psm_7dd83f76'
warnings.warn('resource_tracker: %r: %s' % (name, e))
/usr/local/lib/python3.7/multiprocessing/resource_tracker.py:229: UserWarning: resource_tracker: '//psm_31aba6be': [Errno 2] No such file or directory: '//psm_31aba6be'
warnings.warn('resource_tracker: %r: %s' % (name, e))
/usr/local/lib/python3.7/multiprocessing/resource_tracker.py:229: UserWarning: resource_tracker: '//psm_0cc2cdc6': [Errno 2] No such file or directory: '//psm_0cc2cdc6'
warnings.warn('resource_tracker: %r: %s' % (name, e))

this why?please