gh-109070: multiprocessing.get_context will not set the start method globally #135678
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| if self._actual_context is None: | ||
| self._actual_context = self._default_context | ||
| return self._actual_context | ||
| return self._actual_context or self._default_context |
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I wish I could say "or perhaps even just return self._default_context?" given the documentation for .get_context() today. BUT code relies on .get_context() to establish the actual set context and thus prevent it from being changed without force=True so that different contexts are not used between API surfaces at the default module level (Lib/multiprocessing/__init__.py sets module level attributes to be the multiprocessing.context._default_context instance attributes)
So I think we really are best off just documenting the existing behavior. As is already done for get_start_method() in the docs right below get_context() - https://docs.python.org/3/library/multiprocessing.html
Examples: All of the things defined in BaseContext that when used have a ctx=self.get_context() call in them. Once something is used with the default context we don't want to allow a set_start_method call to change it.
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