如何使用相同的参数运行多个函数？

Question

我在python中使用多重处理。这是我的代码。

def myfun(soup):
    ...
    return param


if __name__ == '__main__':
    res = requests.get('https://www.example.com', headers = headers, timeout = 1)
    res.encoding = 'GB18030'
    soup = BeautifulSoup(res.text, 'lxml')

    with multiprocessing.Pool(4) as p:
        val = p.map(myfun, [soup, soup])#same input for testing

但是它返回：

回溯（最近通话最近一次）：

File "C:\main.py", line 1843, in <module>
    val = p.map(myfun, [soup, soup])
  File "C:\Program Files\Python37\lib\multiprocessing\pool.py", line 268, in map
    return self._map_async(func, iterable, mapstar, chunksize).get()
  File "C:\Program Files\Python37\lib\multiprocessing\pool.py", line 657, in get
    raise self._value
  File "C:\Program Files\Python37\lib\multiprocessing\pool.py", line 431, in _handle_tasks
    put(task)
  File "C:\Program Files\Python37\lib\multiprocessing\connection.py", line 206, in send
    self._send_bytes(_ForkingPickler.dumps(obj))
  File "C:\Program Files\Python37\lib\multiprocessing\reduction.py", line 51, in dumps
    cls(buf, protocol).dump(obj)
RecursionError: maximum recursion depth exceeded while pickling an object

为什么会出现此错误？

如何解决？