Python簡單ProcessPoolExecutor示例不會工作

Question

我正在嘗試多線程在Python 3中，但我不明白爲什麼我的示例將無法工作。它應該只是打印數字，並作爲確認再次打印數字。 但它會遇到很多錯誤。

代替

from concurrent import futures 

def print_me(num): 
    print('Zahl: ' + str(num)) 
    return num 


def say_bye(job): 
    num = job.result() 
    print(str(num) + ' is out!') 


def test_multi(): 
    num_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] 
    with futures.ProcessPoolExecutor(max_workers=4) as executor: 
     for num in num_list: 
      job = executor.submit(print_me, num) 
      job.add_done_callback(say_bye(job)) 

test_multi() 

從理論上說，：

for num in num_list: 
    job = executor.submit(print_me, num) 
    job.add_done_callback(say_bye(job))` 

我可以利用這一點，還是？

executor.map(print_me, num_list) 

Answer 1

要獲取該代碼運行我只需要添加：

**if __name__ == "__main__":** 
    test_multi()