python -> time a while loop has been running

Question

i have a loop that runs for up to a few hours at a time. how could I have it tell me how long it has been at a set interval?

just a generic...question

EDIT: it's a while loop that runs permutations, so can i have it print the time running every 10 seconds?

Answer 1

Instead of checking the time on every loop, you can use a Timer object

import time
from threading import Timer

def timeout_handler(timeout=10):
    print time.time()
    timer = Timer(timeout, timeout_handler)
    timer.start()

timeout_handler()
while True:
    print "loop"
    time.sleep(1)

Answer 2

As noted, this is a little bit of a nasty hack, as it involves checking the time every iteration. In order for it to work, you need to have tasks that run for a small percentage of the timeout - if your loop only iterates every minute, it won't print out every ten seconds. If you want to be interrupted, you might consider multithreading, or preferably if you are on linux/mac/unix, signals. What is your platform?

import time

timeout = 10
first_time = time.time()
last_time = first_time
while(True):
    pass #do something here
    new_time = time.time()
    if  new_time - last_time > timeout:
        last_time = new_time
        print "Its been %f seconds" % (new_time - first_time)

Output:

Its been 10.016000 seconds
Its been 20.031000 seconds
Its been 30.047000 seconds