Python 3.13.10 or Python 3.14.1 only: ValueError: Cannot register "UNREGISTER","rtype":"semlock","base64_name" for automatic cleanup: unknown resource type #475
Description
After upgrading from python 3.13.9 to 3.13.10 I see a series of setup and teardown errors in joblib/externals/loky/backend/resource_tracker.py:
import numpy as np
from joblib import Parallel, delayed
def is_memmap(obj):
return isinstance(obj, np.memmap)
result = Parallel(n_jobs=2, max_nbytes=1e6)(
delayed(is_memmap)(np.ones(int(i)))
for i in [1e2, 1e4, 1e6])
print(result)$ python
Python 3.13.10 (main, Dec 2 2025, 19:48:51) [Clang 21.1.4 ] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import joblib
>>> joblib.__version__
'1.5.2'
...
ValueError: Cannot register "REGISTER","rtype":"semlock","base64_name" for automatic cleanup: unknown resource type ("L2xva3ktMTk4NTQ2NC1lN3N1NWtwMQ=="}). Resource type should be one of the following: ['noop', 'folder', 'file', 'semlock']
...
ValueError: Cannot register "UNREGISTER","rtype":"semlock","base64_name" for automatic cleanup: unknown resource type ("L2xva3ktMTk4NTQ2NC1rNnhuanRteg=="}). Resource type should be one of the following: ['noop', 'folder', 'file', 'semlock']
...
Similar to previous issues: joblib/joblib#1738, #459