python-threadpoolexecutor阻塞。如何解除阻塞

你得不到预期的输出 a handful of threads would have output at once 因为你没有开始 a handful of threads . 一次只能创建一个线程来执行单个任务,这是 get_instance() 功能。

您可以使用以下代码获得接近所需输出的内容:

import datetime as dt
from concurrent.futures import ThreadPoolExecutor
import os
import threading
import time


def handle_instance(h):
    t = dt.datetime.time(dt.datetime.now())
    print('[{}] Got instance {}'.format(t, h))
    print('[{}] Result is {}'.format(t, h.result()))
    print(id(t))


def task():
    print("Executing our Task on Process: {}".format(os.getpid()))
    time.sleep(3)
    return 1


def main():
    with ThreadPoolExecutor(3) as th_exec:
        for dummy in range(3):
            th_future = th_exec.submit(task)
            th_future.add_done_callback(handle_instance)


if __name__ == "__main__":
    try:
        while True:
            print('A new cycle of execution just started...')
            threading.Thread(target=main, daemon=True).start()
            time.sleep(5)
    except KeyboardInterrupt:
        raise SystemExit('\nexit by user')

输出:

A new cycle of execution just started...
Executing our Task on Process: 2528
Executing our Task on Process: 2528
Executing our Task on Process: 2528
[10:40:19.100711] Got instance <Future at 0x262342a9320 state=finished returned int>
[10:40:19.100711] Got instance <Future at 0x2623425e128 state=finished returned int>
[10:40:19.100711] Result is 1
[10:40:19.100711] Result is 1
[10:40:19.100711] Got instance <Future at 0x26233fe3ef0 state=finished returned int>
[10:40:19.100711] Result is 1

exit by user