Inconsistent behaviour of multiprocessing.shared_memory

Bug report

Bug description:

An example code already exists in the documentation (see from here: The following example demonstrates a practical use of the SharedMemory class with NumPy arrays, accessing the same numpy.ndarray from two distinct Python shells).

The code executes fine as expected and mentioned there until one closes the terminals which report warnings.

When the second terminal is closed: /home/souradeep/miniconda/envs/py39/lib/python3.9/multiprocessing/resource_tracker.py:216: 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 '

and when the first terminal is closed: /home/souradeep/miniconda/envs/py39/lib/python3.9/multiprocessing/resource_tracker.py:229: UserWarning: resource_tracker: '/trial': [Errno 2] No such file or directory: '/trial'

This can have implications when one tries to use the feature somewhere in an application (see an example).

CPython versions tested on:

3.9

Operating systems tested on:

Linux

Linked PRs

• gh-119126

从 multiprocessing 文档中的共享内存示例开始，检查 multiprocessing/resource_tracker.py，重点关注报告中复现的关闭时警告。查看链接的 PR gh-119126 及其测试（如果有）；当文档中的示例在关闭时不再产生报告的 resource-tracker 警告后，该 issue 即完成。