python进程池的使用注意事项

import requests
from bs4 import BeautifulSoup
from multiprocessing import Pool, current_process
def get_title(i):    
print('start', current_process().name)    
title_list = []    
url = 'https://movie.douban.com/top250?start={}&filter='.format(i*25)    
r = requests.get(url)    
soup = BeautifulSoup(r.content, 'html.parser')    
lis = soup.find('ol', class_='grid_view').find_all('li')    
for li in lis:        
title = li.find('span', class_="title").text        
# return title        
title_list.append(title)        
print(title)    
return(title_list)if __name__ == '__main__':    
pool = Pool()    
for i in range(10):        
pool.apply_async(get_title, (i, ))    
pool.close()    
pool.join()    
print('finish')