Closed
Description
SharedMemory.unlink() contains a import which can fail if called during interpreter shutdown.
For example when working with SharedMemory as the buffer for a numpy array it is useful to create a wrapper object to ensure that clean up is done with the object is deleted.
#import numpy as np
from multiprocessing import shared_memory
class ShArray:
def __init__(self):
self.shared_memory = shared_memory.SharedMemory(create=True, size=400)
#self.array = np.ndarray((10,10), dtype="i4", buffer=self.shared_memory.buf)
def __del__(self):
self.shared_memory.close()
self.shared_memory.unlink()
a1 = ShArray()(Commented lines show my typical usage, but are not need to demonstrate the issue)
Exception ignored in: <function ShArray.__del__ at 0x7f36eee510d0>
Traceback (most recent call last):
File "/home/sam/git/cpython/test_shared_mem2.py", line 13, in __del__
File "/home/sam/git/cpython/Lib/multiprocessing/shared_memory.py", line 240, in unlink
ImportError: sys.meta_path is None, Python is likely shutting down
/home/sam/git/cpython/Lib/multiprocessing/resource_tracker.py:224: UserWarning: resource_tracker: There appear to be 1 leaked shared_memory objects to clean up at shutdown
warnings.warn('resource_tracker: There appear to be %d '
This happens on 3.8 and current main, both on Linux x86-64.
Patch to follow