Question

我正在由3个工作人员创建线程池，并为执行程序分配10个任务。

我执行任务时没有任何输出。

from concurrent.futures import ThreadPoolExecutor
import threading
import random

def task(n):
 import sleep
 sleep.time(5)
 print("Processing {}".format(n))

def main():
    executor = ThreadPoolExecutor(max_workers=3)    
    for each in range(10):
        executor.submit(task, each)

if __name__ == '__main__':
    main()

Answer 1

尝试在函数中导入sleep时，会遇到ImportError异常。

将功能更改为

import time
def task(n):
    time.sleep(3)
    print("Processing {}".format(n))

如果您想查看这些错误（来自原始task），请更改main以累积期货并将其退还。然后遍历期货并打印结果。

...

def main():
    executor = ThreadPoolExecutor(max_workers=3)
    futures = []
    for each in range(10):
        futures.append(executor.submit(task, each))
    return futures

if __name__ == '__main__':
    futures = main()
    for future in futures:
        print(future, future.exception())

会产生这样的东西

>>>
<Future at 0x34712d0 state=finished raised ImportError> No module named 'sleep'
<Future at 0x34b0e70 state=finished raised ImportError> No module named 'sleep'
<Future at 0x34b0ff0 state=finished raised ImportError> No module named 'sleep'
<Future at 0x34be170 state=finished raised ImportError> No module named 'sleep'
<Future at 0x34be1f0 state=finished raised ImportError> No module named 'sleep'
<Future at 0x34be270 state=finished raised ImportError> No module named 'sleep'
<Future at 0x34be2f0 state=finished raised ImportError> No module named 'sleep'
<Future at 0x34be370 state=finished raised ImportError> No module named 'sleep'
<Future at 0x34be3f0 state=finished raised ImportError> No module named 'sleep'
<Future at 0x34be470 state=finished raised ImportError> No module named 'sleep'
>>>

Answer 2

为补充wwii的答案，在使用ThreadPoolExecutor之前，我建议首先使用普通线程进行测试。

由于ThreadPoolExecutor旨在在您想要获得结果（future.result()）时引发异常，但是有时我们甚至不关心结果。在这种情况下，任务将隐式失败，而不会发出任何通知。

线程池执行程序不执行多个线程

2 个答案: