Monitoring a real-time data stream with a flask we

This is based on the answer posted at https://stackoverflow.com/a/13388915/819544

I would like to monitor a stream of data and push it to a front-end similar to the answer above, but where the stream starts generating/monitoring data as soon as the app kicks off, and the client always sees the current state of the data steam (which keeps running whether or not they are requesting data from the server).

I'm pretty sure I need to separate the data stream from the front-end via threading, but I'm not very practiced with threaded/asynchronous programming and believe I'm doing it wrong. Maybe instead of threading I need to be using multiprocessing? Here's roughly what I'm trying to do (modified from the answer linked above):

app.py

#!/usr/bin/env python
from __future__ import division
import itertools
import time
from flask import Flask, Response, redirect, request, url_for
from random import gauss
import threading

app = Flask(__name__)

# Generate streaming data and calculate statistics from it
class MyStreamMonitor(object):
    def __init__(self):
        self.sum   = 0
        self.count = 0
    @property
    def mu(self):
        try:
            outv = self.sum/self.count
        except:
            outv = 0
        return outv
    def generate_values(self):
        while True:
            time.sleep(.1)  # an artificial delay
            yield gauss(0,1)
    def monitor(self, report_interval=1):
        print "Starting data stream..."
        for x in self.generate_values():
            self.sum   += x
            self.count += 1 

stream = MyStreamMonitor()

@app.route('/')
def index():
    if request.headers.get('accept') == 'text/event-stream':
        def events():
            while True:
                yield "data: %s %d\n\n" % (stream.count, stream.mu)
                time.sleep(.01) # artificial delay. would rather push whenever values are updated. 
        return Response(events(), content_type='text/event-stream')
    return redirect(url_for('static', filename='index.html'))

if __name__ == "__main__":
    # Data monitor should start as soon as the app is started.
    t = threading.Thread(target=stream.monitor() )
    t.start()
    print "Starting webapp..." # we never get to this point.
    app.run(host='localhost', port=23423)

static/index.html

<!doctype html>
<title>Server Send Events Demo</title>
<style>
  #data {
    text-align: center;
  }
</style>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>
if (!!window.EventSource) {
  var source = new EventSource('/');
  source.onmessage = function(e) {
    $("#data").text(e.data);
  }
}
</script>
<div id="data">nothing received yet</div>

This code doesn't work. The "Starting webapp..." message never prints, nor do the normal flask messages, and visiting the served URL confirms the app isn't running.

How do I get the data monitor to run in the background in such a way that flask can access the values it's seeing and push the current state up to the client (better even: as long as the client is listening, push the current state when the relevant values change)?

I just needed to change this line

t = threading.Thread(target=stream.monitor())

to this:

t = threading.Thread(target=stream.monitor)

Monitoring a real-time data stream with a flask we

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