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class Timer(Thread):

"""Call a function after a specified number of seconds:

       t = Timer(30.0, f, args=None, kwargs=None)

       t.start()

       t.cancel()     # stop the timer's action if it's still waiting

"""

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import datetime

from flask import Flask

import threading

app = Flask(__name__)

def loop(msg):

    print(msg)

    timer = threading.Timer(3, loop, (f"start check: {datetime.datetime.now()}",))

    timer.daemon = True

    timer.start()

@app.route("/")

def test():

   print("hello world")

if __name__ == '__main__':

    loop(f"start check: {datetime.datetime.now()}")

    app.run()

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start check: 2022-06-15 10:31:56.069280

 * Serving Flask app 'test' (lazy loading)

 * Environment: production

   WARNING: This is a development server. Do not use it in a production deployment.

   Use a production WSGI server instead.

 * Debug mode: off

 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)

start check: 2022-06-15 10:31:56.069321

start check: 2022-06-15 10:31:59.071218

start check: 2022-06-15 10:32:02.071914

start check: 2022-06-15 10:32:05.074362

start check: 2022-06-15 10:32:08.079799

start check: 2022-06-15 10:32:11.082420

start check: 2022-06-15 10:32:14.082753

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import datetime

import time

from flask import Flask

import threading

app = Flask(__name__)

def task():

    print(f"start check: {datetime.datetime.now()}")

def loop():

    # 使用while True的方式保持这个Timer线程不停止

    while True:

        task()

        time.sleep(3)

@app.route("/")

def test():

    print("hello world")

if __name__ == '__main__':

    timer = threading.Timer(3, loop)

    timer.daemon = True

    timer.start()

    app.run()