Unable to mqtt_client publish inside a class - python-2.7

Question

I'm trying to use Paho MQTT Client and Multiprocessing to send temperature with defined interval. However, publish command is not working inside class. I've checked self.mqtt_client inside scheduler it has the Client object.
Is there anyone that can address problem for me?
Everything inside class is working except Scheduler.
def scheduler(self, topic, interval):
if interval != 0:
while True:
if topic == "temp":
print("Temperature published " + interval) #It's working.
self.mqtt_client.publish(topic, interval , 0 , False) #There is no error/output about this line
time.sleep(int(interval))
else:
pass
Class:
class Switcher:
config = None
mqtt_client = None
mqtt_connected = False
switches = {}
stages = {}
def __init__(self, config):
self.config = config
for switch_cfg in self.config['switches']:
self.switches[switch_cfg['topic_set']] = Switch(int(switch_cfg['gpio']), switch_cfg['topic_status'], switch_cfg['initial'])
def scheduler(self, topic, interval):
if interval != 0:
while True:
if topic == "temp":
print("Temperature published " + interval) #It's working.
self.mqtt_client.publish(topic, interval , 0 , False) #There is no error/output about this line
time.sleep(int(interval))
else:
pass
def mqtt_connect(self):
if self.mqtt_broker_reachable():
self.verbose('Connecting to ' + self.config['mqtt_host'] + ':' + self.config['mqtt_port'])
self.mqtt_client = mqtt.Client(self.config['mqtt_client_id'])
if 'mqtt_user' in self.config and 'mqtt_password' in self.config:
self.mqtt_client.username_pw_set(self.config['mqtt_user'], self.config['mqtt_password'])
self.mqtt_client.on_connect = self.mqtt_on_connect
self.mqtt_client.on_disconnect = self.mqtt_on_disconnect
self.mqtt_client.on_message = self.mqtt_on_message
try:
self.mqtt_client.connect(self.config['mqtt_host'], int(self.config['mqtt_port']), 10)
for switch_cfg in self.config['switches']:
self.mqtt_client.subscribe(switch_cfg['topic_set'], 0)
self.mqtt_client.loop_forever()
except:
self.error(traceback.format_exc())
self.mqtt_client = None
else:
self.error(self.config['mqtt_host'] + ':' + self.config['mqtt_port'] + ' not reachable!')
def mqtt_on_connect(self, mqtt_client, userdata, flags, rc):
self.mqtt_connected = True
for switch_ios in self.config['switches']:
self.mqtt_client.publish(self.config['station_status'], "available", 0, False)
self.mqtt_client.publish(switch_ios['topic_status'], self.switches[switch_ios['topic_set']].get_state(), 0, False)
temp_interval = 1
temp_process = multiprocessing.Process(target=self.scheduler, args=("temp",str(temp_interval),))
temp_process.start()
self.verbose('...mqtt_connected!')
def mqtt_broker_reachable(self):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.settimeout(5)
try:
s.connect((self.config['mqtt_host'], int(self.config['mqtt_port'])))
s.close()
return True
except socket.error:
return False
def start(self):
self.mqtt_connect()

Answer 1

You mqtt_connect function will never return.
self.mqtt_client.loop_forever() Will block until self.mqtt_client.disconnect() is called.
You should probably be using self.mqtt_client.loop_start() which will run the client loop on it's own thread in the background. You can call self.mqtt_client.loop_stop() when you want to shut the client down.