run sched function in a separate thread so that new event can be pushed into the queue, will quite when the queue becomes empty

sched in a thread

import sched, time
from threading import Thread

def print_time(a='default'):
    print("From print_time", time.time(), a)
    
s = sched.scheduler(time.time, time.sleep)
s.enterabs(time.time()+1, 0, print_time, argument=('before',))

def start():
    print('start')
    s.run()

t = Thread(target=start)
t.start()

for i in range(10):
    s.enterabs(time.time() + i, 1, print_time, argument=('item '+str(i),))