Example of calling function every N seconds precisely.

gistfile1.py

import threading
import time
import psutil
import os
from datetime import datetime


def precise_repeat(f, interval=1.0, run=False):
    delay = interval - (time.time() % interval)
    threading.Timer(delay, precise_repeat, (f, interval, True)).start()

    if run:
        threading.Thread(target=f).start()


def worker():
    p = psutil.Process(os.getpid())
    print os.getpid(), p.get_num_threads(), time.time(), datetime.now()


if __name__ == "__main__":
    precise_repeat(worker)