问为什么泛美卫生组织python客户端发布短消息而不发布长消息？

EN

while True:
    print('')
    command_input = input()
    if command_input == 'q':
        break
    mcp = Mqtt_command_publisher
    mcp.publish_command(device_ids, command_input)

class Mqtt_command_bl:
    def update_minutes_to_run_at(json):
        if not json['device_ids']:
            return 'Request must contain device ids'

        device_ids = json['device_ids']
        minutes_to_run_at = json['minutes_to_run_at']

        minutes_to_run_at_command_section = ''
        for i in minutes_to_run_at:
            m = '"{}",'.format(i)
            if i == minutes_to_run_at[len(minutes_to_run_at) - 1]:
                m = '"{}"'.format(i)
            minutes_to_run_at_command_section += m

        #command_input = 'jq \'.+{{minutes_to_run_at:[{}]}}\' /home/pi/hallmonitor_lite/config.json > /home/pi/hallmonitor_lite/tmp.json && mv /home/pi/hallmonitor_lite/tmp.json /home/pi/hallmonitor_lite/new_config.json'.format(minutes_to_run_at_command_section)
        command_input = 'mkdir /home/pi/hallmonitor_lite/hello_world'

        mcp = Mqtt_command_publisher
        mcp.publish_command(device_ids, command_input)

        return 'Success'

class Mqtt_command_publisher:
    def publish_command(device_ids, command_input):
        mqtt_msg = json.dumps({'device_ids':device_ids,'command':command_input})
        print('\n{}'.format(mqtt_msg))
        client = mqtt.Client()
        client.connect('********', ****, 30)
        client.publish('topic/commands', mqtt_msg)
        client.disconnect()

device_id = 0

with open('/home/pi/hallmonitor_lite/config.json') as json_data_file:
    data = json.load(json_data_file)

    device_id = data['device_id']

def on_connect(client, userdata, flags, rc):
    print("Connected with result code: " + str(rc))
    client.subscribe("topic/commands")

def on_message(client, userdata, msg):
    mqtt_message = msg.payload.decode()
    print(mqtt_message)
    ids_and_command = json.loads(mqtt_message)
    if str(device_id) in ids_and_command['device_ids'] or not ids_and_command['device_ids']:
        print(('Executing: {}').format(ids_and_command['command']))
        os.system(ids_and_command['command'])



client = mqtt.Client()
client.connect("********", ****, 30)

client.on_connect = on_connect
client.on_message = on_message

client.loop_forever()