多處理.Queue可能會丟失它內部的元素

Question

我使用multiprocessing.Queue來處理廣告創建。但是，在使用Queue.get（）時，似乎有些元素會丟失（例如，我在隊列中放置了10個廣告，但在多處理完成後只處理了8個）。

的代碼是：

from multiProcessing import Process, Queue, JoinableQueue 

def create_ad(origin_queue, ad_queue): 
    ''' ad creation''' 
    for ad in iter(origin_queue.get, None): 
     try: 
      # do sth else 

      ad_queue.put(ad) 
     except: 
      pass 
      # actually there exists logging here, no error outside 
     finally: 
      origin_queue.task_done() 
    origin_queue.task_done() 

if __name__ == '__main__': 

    origin_queue = JoinableQueue() 
    # mock to put ads inside 
    ads = [1,2,3,4,5]   
    [ origin_queue.put(ad) for ad in ads ] 

    ad_queue = Queue() 
    process_list = [] 
    for p in range(4): # PROCESS_NUM 
     process = Process(target=create_ad, args=(origin_queue, ad_queue)) 
     process_list.append(process) 
    for process in process_list: 
     process.daemon = True 
     process.start() 

    origin_queue.join() 

    for process in process_list: 
     origin_queue.put(None) 
    origin_queue.join() 

    while not ad_queue.empty(): 
     ad = ad_queue.get() # number of ad got here is different from ads put inside it 

是我的隊列的用法錯了嗎？

Answer 1

你是隱藏，當你做到這一點所發生的錯誤：

try: 
     ad_queue.put(ad) 
    except: 
     pass 

爭取你的隊列中取出except

Answer 2

加擋，否則會引發異常，你已經丟棄，當滿或空。