import threading
import time

def gen():
    while True:
        yield 3

def loop_on_func():
    g = gen()
    next(g)
    while True:
        g.send(1)

workers = []
for _ in range(4):
    worker = threading.Thread(target=loop_on_func)
    worker.daemon = True
    workers.append(worker)
for worker in workers:
    worker.start()

time.sleep(0.1)

# for worker in workers: worker.join()