Python - Threadpoolexecutor Blocking. How To Unblock

The following code is blocking: import threading from concurrent.futures import ThreadPoolExecutor import os from pprint import pprint import time def sleep(seconds): for i i

Solution 1:

You don't get expected output a handful of threads would have output at once because you don't start a handful of threads. You create only one thread at a time to perform a single task which is a call of get_instance() function.

You may get something close to the desired output with following code:

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


defhandle_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))


deftask():
    print("Executing our Task on Process: {}".format(os.getpid()))
    time.sleep(3)
    return1defmain():
    with ThreadPoolExecutor(3) as th_exec:
        for dummy inrange(3):
            th_future = th_exec.submit(task)
            th_future.add_done_callback(handle_instance)


if __name__ == "__main__":
    try:
        whileTrue:
            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')

Output:

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 is1
[10:40:19.100711] Result is1
[10:40:19.100711] Got instance <Future at 0x26233fe3ef0 state=finished returned int>
[10:40:19.100711] Result is1

exit by user