New submission from Kernel Plevitsky : I'm not sure if this is a bug or my carelessness. I cannot call set_start_method () if multiprocessing.Value() is declared in the class above than "if __name__ ==" __main__ "" The documentation for Value did not describe this. I have attached a code playing this moment. Sorry for my English ---------- assignee: docs@python components: Documentation files: test.py messages: 371933 nosy: Kernel Plevitsky, docs@python priority: normal severity: normal status: open title: class multiprocessing.Value calls set_start_method type: behavior versions: Python 3.5, Python 3.8 Added file: https://bugs.python.org/file49256/test.py _______________________________________ Python tracker https://bugs.python.org/issue41050 _______________________________________