Pure Python & Flask server-side event source

index.html

<script>
var stream = new EventSource('/api/stream');
stream.onmessage = function(e) {
    console.info(e.data);
};
</script>

server.py

from queue import Queue
from flask import Flask, render_template, request

app = Flask(__name__)
app.debug = True

queue = Queue()

def event_stream():
    while True:
    	# Question: how to break out of this loop when the app is killed?
        message = queue.get(True)
        print("Sending {}".format(message))
        yield "data: {}\n\n".format(message)


@app.route('/')
def hello():
    return render_template('index.html')


@app.route('/api/stream')
def stream():
    return flask.Response(event_stream(), mimetype="text/event-stream")


@app.route('/api/post', methods=['GET'])
def api_parse_sentence():
    queue.put(request.args.get('sentence'))
    return "OK"


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