While loop waits without stopping until the time.sleep finishes

Question

I have a while loop in a thread which checks a webstream every 10 minutes.

while not stop_event.is_set():
    time.sleep(600)
    response = requests.get(api_url, headers=headers, params=params)
    if response.status_code==200:
        print("UPDATED")
    else:
        print("NOT UPDATED")

But if the not stop_event.is_set() changed to False before 10 minutes, Still the while loop waits 10 minutes and executes the rest of the code and then exits

    response = requests.get(api_url, headers=headers, params=params)
    if response.status_code==200:
        print("UPDATED")
    else:
        print("NOT UPDATED")

I want to quit immediately as the not stop_event.is_set() changed to False without witing time.sleep(600) to finish

Thanks in advance

Answer 1

Instead of time.sleep, which is blocking, you could use threading.Event.wait which will return immediately if the internal flag is set:

while not stop_event.is_set():
    if stop_event.wait(600):
        break # or use "return" if you want the entire function to end
    response = requests.get(api_url, headers=headers, params=params)
    if response.status_code == 200:
        print("UPDATED")
    else:
        print("NOT UPDATED")

A reproducible example:

import time
import threading


def run_in_thread(stop_event):
    while not stop_event.is_set():
        if stop_event.wait(5):
            print(f"{time.strftime('%H:%M:%S', time.localtime())}: Stopped.")
            return
        print(f"{time.strftime('%H:%M:%S', time.localtime())}: Running.")


if __name__ == '__main__':
    stop_event = threading.Event()
    t = threading.Thread(target=run_in_thread, args=(stop_event,))
    t.start()
    time.sleep(16)
    stop_event.set()