def start(self):
        assert self._popen is None, 'cannot start a process twice'
        assert self._parent_pid == os.getpid(), \
               'can only start a process object created by current process'
        assert not _current_process._daemonic, \
               'daemonic processes are not allowed to have children'
        _cleanup()
        if self._Popen is not None:
            Popen = self._Popen
        else:
            from .forking import Popen
        self._popen = Popen(self)
        _current_process._children.add(self)
Start child process
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/python/Lib/multiprocessing/process.py/Process.start