多线程 pool.map为什么会报错

Question

import requests
from lxml import etree
from multiprocessing import Pool
from bs4 import BeautifulSoup
import lxml
import pymysql


def prepare_url():
    base_url = "https://movie.douban.com/top250?start="
    full_urls = []
    for i in range(0, 10):
        # 准备全路径
        full_url = base_url + str(i * 25)
        full_urls.append(full_url)
    return full_urls


def get_html(url):
    headers = {'User-Agent': 'Mozilla/5.0 (compatible; MSIE 9.0; Windows NT)'}
    try:
        html = requests.get(url=url, headers=headers).text
    except:
        print("爬取失败")


def parse_html(html):
    soup = BeautifulSoup(html, 'lxml')
    div_list = soup.find_all('div', {'class': 'info'})
    message_list = []
    for div in div_list:
        title = div.find('a').find('span').text
        score = div.find_all('div', {'class': 'star'}).find('span', {'class': 'rating_num'}).text
        movie_url = div.find('a')['href']
        dict = {'movie': title, 'rating_num': score, 'url': movie_url}
        message_list.append(dict)
    return message_list

def get_data(url):
    html = get_html(url)
    datas = parse_html(html)



if __name__ == '__main__':
    full_urls = prepare_url()
    # print(full_urls)
    pool = Pool(10)
    data = pool.map(get_data,full_urls)
    print(data)

TypeError: object of type 'NoneType' has no len()

Answer 1

你把最重要的错误信息都省略了……不想看源码，建议发完整错误信息