BUG: Memory leak calling hash() on np.datetime64 object #29397
Description
Describe the issue:
Memory leak, when calling hash() on np.datetime64 instance that is non-empty. gc.collect() does not free memory, no ref counts to python objects leaks found with objgraph library, using show_growth(). Seems the leak is on the C side, possibly in
numpy/numpy/_core/src/multiarray/datetime.c
Line 2832 in d02611a
EDIT: see comment below.
tracemalloc points at the hash() call.
Run the code example and observe the memory usage grow rapidly.
Reproduce the code example:
import numpy as np
#dt_obj = np.datetime64() #no leak with empty object
dt_obj = np.datetime64(10, "Y")
while True:
hash(dt_obj) #leaks here
print("leak")Error message:
Python and NumPy Versions:
Python 3.13.3, numpy 2.2.6
Runtime Environment:
[{'numpy_version': '2.2.6',
'python': '3.13.3 (tags/v3.13.3:6280bb5, Apr 8 2025, 14:47:33) [MSC v.1943 '
'64 bit (AMD64)]',
'uname': uname_result(system='Windows', release='10', version='10.0.17763', machine='AMD64')},
{'simd_extensions': {'baseline': ['SSE', 'SSE2', 'SSE3'],
'found': ['SSSE3',
'SSE41',
'POPCNT',
'SSE42',
'AVX',
'F16C',
'FMA3',
'AVX2'],
'not_found': ['AVX512F',
'AVX512CD',
'AVX512_SKX',
'AVX512_CLX',
'AVX512_CNL',
'AVX512_ICL']}},
{'filepath': 'C:\\Program '
'Files\\Python\\Python313\\Library\\bin\\libiomp5md.dll',
'internal_api': 'openmp',
'num_threads': 6,
'prefix': 'libiomp',
'user_api': 'openmp',
'version': None},
{'filepath': 'C:\\Program '
'Files\\Python\\Python313\\Library\\bin\\mkl_rt.2.dll',
'internal_api': 'mkl',
'num_threads': 6,
'prefix': 'mkl_rt',
'threading_layer': 'intel',
'user_api': 'blas',
'version': '2025.1-Product'}]
Context for the issue:
No response