[issue39959] (Possible) bug on multiprocessing.shared_memory

[Jeff Fischer]

Jeff Fischer <jeff.fischer at benedat.com> added the comment:

I've run into the same problem. It appears that the SharedMemory class is assuming that all clients of a segment are child processes from a single parent, and that they inherit the same resource_tracker. If you run separate, unrelated processes, you get a separate resource_tracker for each process. Then, when a process does a close() followed by a sys.exit(), the resource tracker detects a leak and unlinks the segment.

In my application, segment names are stored on the local filesystem and a specific process is responsible for unlinking the segment when it is shut down. I was able to get this model to work with the current SharedMemory implementation by having processes which are just doing a close() also call resource_tracker.unregister() directly to prevent their local resource trackers from destroying the segment.

I imagine the documentation needs some discussion of the assumed process model and either: 1) a statement that you need to inherit the resource tracker from a parent process, 2) a blessed way to call the resource tracker to manually unregister, or 3) a way to disable the resource tracker when creating the SharedMemory object.

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nosy: +jfischer

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue39959>
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