how to know flask_socketio is connected

[6273parastu]

hi, i need to know connection socketio is alive or is connected when i use in start_background_task, for e.x:
@socketio.on('connect')
@authenticated_only
def on_connect():
connection_id = request.sid
socketio.start_background_task(target=background_thread_from_stream, app=current_app._get_current_object(), connection_id=connection_id)

def background_thread_from_stream(self, app, connection_id):
with app.app_context():
while connection_id is connected:
do_somtitng()

[miguelgrinberg]

When a client disconnects the disconnect handler is invoked. You can keep track of your users in your application, adding users in the connect handler, and removing them in the disconnect handler.