def join(self, timeout=None):
        assert self._parent_pid == os.getpid(), 'can only join a child process'
        assert self._popen is not None, 'can only join a started process'
        res = self._popen.wait(timeout)
        if res is not None:
            _current_process._children.discard(self)
Wait until child process terminates
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/python/Lib/multiprocessing/process.py/Process.join