Flask did not refresh the content

my development environment is the vagrant virtual machine under linux. I configured the environment using flask+gunicorn+supervisor+nginx and successfully output "hello world", below is my directory

where microblog is my project name, and app is a (and now only one) application;flask is my virtualenv.
_ _ init__.py

from flask import Flask

app = Flask(__name__)
from app import views

run.py

-sharp!flask/bin/python
from app import app
from werkzeug.contrib.fixers import ProxyFix
from datetime import timedelta


app.config["DEBUG"] = True
app.config["SEND_FILE_MAX_AGE_DEFAULT"] = timedelta(seconds = 1)
app.config["PERMANENT_SESSION_LIFETIME"] = timedelta(seconds=1)

if __name__ == "__main__":
    app.wsgi_app = ProxyFix(app.wsgi_app)
    app.run()

views.py

from app import app

@app.route("/")
@app.route("/index")
def index():
    return "Hello world!"

everything is fine here. But when I put return "hello worldview" Change to other times when the browser output is still hello world. It won"t change until I restart the process through supervisor.

I don"t know where the reason is, please give me your advice aloud!