forking.py 文件源码

def poll(self, flag=os.WNOHANG):
            if self.returncode is None:
                while True:
                    try:
                        pid, sts = os.waitpid(self.pid, flag)
                    except os.error as e:
                        if e.errno == errno.EINTR:
                            continue
                        # Child process not yet created. See #1731717
                        # e.errno == errno.ECHILD == 10
                        return None
                    else:
                        break
                if pid == self.pid:
                    if os.WIFSIGNALED(sts):
                        self.returncode = -os.WTERMSIG(sts)
                    else:
                        assert os.WIFEXITED(sts)
                        self.returncode = os.WEXITSTATUS(sts)
            return self.returncode