from flask import Flask,render_template

app = Flask(__name__)

@app.route('/')
def index():
    
    print('deneme')

    return render_template('index.html')

if __name__ == '__main__':
    app.run(debug=True)

from flask import Flask,render_template 
import threading,time

app = Flask(__name__) 

@app.route('/') 
def index(): 
    return render_template('index.html')
def start_new_thread():
    def worker(arg1,arg2):
        while(True):
            print("deneme")
            time.sleep(2)
    thread = threading.Thread(target=worker,args=("your argument","sencond one"))
    thread.start();
if __name__ == '__main__':
    start_new_thread()
    app.run(debug=True)