Display a countdown for the python sleep function

Question

I am using time.sleep(10) in my program. Can display the countdown in the shell when I run my program?

>>>run_my_program()
tasks done, now sleeping          


        

Answer 1

time.sleep() may return earlier if the sleep is interrupted by a signal or later (depends on the scheduling of other processes/threads by OS/the interpreter).

To improve accuracy over multiple iterations, to avoid drift for large number of iterations, the countdown may be locked with the clock:

#!/usr/bin/env python
import sys
import time

for i in reversed(range(1, 1001)):
    time.sleep(1 - time.time() % 1) # sleep until a whole second boundary
    sys.stderr.write('\r%4d' % i)