twisted-flask-doubt.py

I have a flask server for voip application. I user sends a http request and then I open port for sending data between clients 
communicating.
I use twisted to create reactor and transfer the data between clients. The reactor is created in the flask function which responds
to the http reqeust.

@app.route('/start_server',methods=['POST'])
def start_server():
	port = reactor.listenTCP(0, Factory())
	port.getHost().port
	reactor.run()
	return jsonify({"port":port})
	
Now other clients can connect to the server and communicate via the twisted reactor's event loop shown below.

Question: After the function start_server() returns and will the reactor started in it will alive like thread?