import multiprocessing import sys modname = 'preloaded_module' if __name__ == '__main__': if modname in sys.modules: raise AssertionError(f'{modname!r} is not in sys.modules') multiprocessing.set_start_method('forkserver') multiprocessing.set_forkserver_preload([modname]) for _ in range(2): p = multiprocessing.Process() p.start() p.join() elif modname not in sys.modules: raise AssertionError(f'{modname!r} is not in sys.modules')