python flask + Server Sent Events(SSE) in Google App Engine(GAE) - google-app-engine

Question

Hi I am trying to do SSE(Server-Sent Events) with python flask quite similar to this question
I am using SSE to plot a real-time graph in the web app.
My codes are working fine when applied in local, but when I deploy it in GAE(Google App Engine), the data does not seem to be returned(yield)
I found that I should make the response header as following
X-Accel-Buffering: no
in this guide here
So, I tried this code on "main.py"
# render "plot.html" and plot the real-time graph
# plot.html gets the value from /chart-data event stream, and update the graph
#app.route('/plot_graph', methods=["GET", "POST"])
def plot_graph():
return render_template('plot.html')
#app.route('/chart-data')
def chart_data():
def generate_random_data():
while True:
# generating random data
json_data = json.dumps(
{'time': datetime.now().strftime('%Y-%m-%d %H:%M:%S'), 'value': random() * 100})
yield f"data:{json_data}\n\n"
time.sleep(0.5)
resp = Response(generate_random_data(), mimetype='text/event-stream')
resp.headers["X-Accel-Buffering"] = "no"
return resp
Also, in "plot.html" file, it is getting values from /chart-data like this
const source = new EventSource("/chart-data");
source.onmessage = function (event) {
const data = JSON.parse(event.data);
...
}
and this also works well when executed in local machine, but not working on GAE..
for the logs and error messages, when I tried the code on local machine,
and went to the root dir, /plot_graph, /chart-data, the log looks like
127.0.0.1 - - [03/Jul/2020 14:14:19] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [03/Jul/2020 14:14:20] "GET /favicon.ico HTTP/1.1" 404 -
127.0.0.1 - - [03/Jul/2020 14:14:23] "GET /plot_graph HTTP/1.1" 200 -
127.0.0.1 - - [03/Jul/2020 14:14:24] "GET /chart-data HTTP/1.1" 200 -
127.0.0.1 - - [03/Jul/2020 14:15:04] "GET /chart-data HTTP/1.1" 200 -
when I went into /plot_graph, I see a GET request from /chart-data and it works fine(/plot_graph shows a real-time graph). Also, when I go into /chart-data, I can see yielded values being displayed on the web.
In the GAE logs,
2020-07-03 05:22:23 default[20200703t141524] "GET / HTTP/1.1" 200
2020-07-03 05:22:23 default[20200703t141524] "GET /favicon.ico HTTP/1.1" 404
2020-07-03 05:22:38 default[20200703t141524] "GET /plot_graph HTTP/1.1" 200
for the GAE, even if I entered /plot_graph, the GET request does not seemed to be happening. and since it is not getting any values, the graph is not plotted(only the frame for the graph is displayed).
Also, I tried to go into /chart-data of GAE web server, but I could not enter and cannot see any GET request in the logs as I saw on the server on local machine.
Please can you help me with this problem?