[issue23060] Assert fails in multiprocessing.heap.Arena.__setstate__ on Windows

[Steve Dower]

Steve Dower added the comment:

That was actually my first hack and it also works. The fundamental problem here is that GetLastError() is not actually meant to indicate *whether* an error has occurred, but when one has occurred it describes what it was.

Indeed, in this case no error has occurred - CreateFileMapping was called and there is a file mapping available. OpenFileMapping is provided if an error is required when the mapping does not already exist.

The best option is definitely a separate method (or parameter) on mmap to open/raise rather than open/create. I may just comment out the assertion with a reference to this bug in the meantime, so that the buildbots aren't getting stuck every time.

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue23060>
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