在每轮开始时每隔 5 分钟运行一次 function

Question

I want to run a function every 5 minutes, it must be at a "round" intervals, for example:

12:05:00, 12:10:00, 12:15:00...

It cannot be like this:

12:06:00, 12:11:00, 12:16:00...

Or like this:

12:05:14, 12:10:14, 12:15:14...

What is the most accurate way to do this in python?

Answer 1

You could use a threading.Timer . You have to do some math to calculate the next run time. datetime has a handy replace method for that.

from datetime import datetime, timedelta
from threading import Timer

def get_sleep_time():
    now = datetime.now()
    next_run = now.replace(minute=int(now.minute / 5) * 5, second=0, microsecond=0) + timedelta(minutes=5)
    return (next_run - now).total_seconds()

def dowork():
    now = datetime.now()
    print('Doing some work at', now)
    schedule_next_run()

def schedule_next_run():
    sleep_time = get_sleep_time()
    print(f'sleeping for {sleep_time} seconds')
    t = Timer(sleep_time, dowork)
    t.daemon = True
    t.start()


print('Starting work schedule')
schedule_next_run()
input('Doing work every 5 minutes. Press enter to exit')

On my system, the function fires within a half millisecond of the target time

Note that the time calculation rounds down and then adds a timedelta to carefully wrap around the end of each hour. You would want to ponder how this will behave around daylight savings changes.

Suggestion : move all this logic to a class to clean it up.

Answer 2

import datetime, time

def some_function():

ran_once = True

while True:
    current_time = datetime.datetime.now()
    if  current_time.minute % 5 == 0 and current_time.second % 60 == 0 and not ran_once:
        print(current_time) # DO YOUR WORK HERE
        ran_once = True

    elif current_time.minute % 5 == 0 or current_time.second % 60 != 0:

        if current_time.second % 60 == 0:
            print("Time to wait:", 5 - (current_time.minute % 5), "minutes and 0 seconds")
        else:
            print("Time to wait:", 4 - (current_time.minute % 5), "minutes and ", end="")
            print(60 - (current_time.second % 60), "seconds")

        time.sleep( (4 -(current_time.minute % 5))*60 + 60 -(current_time.second % 60))

        ran_once = False

The above code runs at intervals of 5 minutes. Initially, the main thread sleeps for the number of seconds required to reach the perfect timestamp. For example, if the program is started at 7:28:30 then it is going to sleep for 90 seconds and then start at 7:30:00. From then on it will wait for 5 minutes before it runs the required functionality again.

Also, I think the performance of firing up at the exact second really varies on how your system handles the threads.

Answer 3

You can use datetime and condition.

import datetime

while True:
    current_time = datetime.datetime.now()
    if current_time.second % 5 == 0 and current_time.minute % 1 == 0 and current_time.microsecond == 0:

        print(current_time)

hope this helps.