Python程序和MySQL之间的连接断开

为什么会出现此错误？

Mysql.connector.errors.DatabaseError：2003（HY000）：无法连接到MySQL服务器n'3.XX.XXX.89'（110）

我正在从MQTT代理收集数据并将其存储在MySQL数据库中。要订阅MQTT代理上的主题，我正在使用Paho MQTT客户端，并且要连接到MySQL数据库服务器，我正在使用MySQL python连接器。我在后台在Amazon EC2 Ubuntu实例（虚拟服务器）上连续运行此python脚本：

import mysql.connector
import paho.mqtt.client as mqtt

#Mysql Settings
db = mysql.connector.connect(host='localhost',
                     user='user_name',
                     password='password',
                     db='db_name')

if db.is_connected():
   db_Info = db.get_server_info()
   print("Connected to MySQL Server version ", db_Info)

cursor = db.cursor()

#MQTT Settings
MQTT_Broker = "3.XX.XXX.89"
MQTT_Port = 1883
Keep_Alive_Interval = 60
MQTT_Topic = "my/publish/#"

#Subscribe
def on_connect(client, userdata, flags, rc):
    mqttc.subscribe(MQTT_Topic, 0)
    print("subscribed")

#Save data into DB Table
def on_message(mosq, obj, msg):
    print("Insert from MQTT")
    print("wait")
    print(msg.topic+" "+str(msg.qos)+" "+str(msg.payload))
    sql = """INSERT INTO gnss (topic, gnssdata) VALUES (%s,%s)"""
    tuple = (msg.topic, msg.payload)
    cursor.execute(sql, tuple)
    db.commit()
    print("Record inserted successfully into gnss table")


def on_subscribe(mosq, obj, mid, granted_qos):
    pass

mqttc = mqtt.Client()

#Assign Event Callbacks
mqttc.on_message = on_message
mqttc.on_connect = on_connect
mqttc.on_subscribe = on_subscribe

#Connect
mqttc.connect(MQTT_Broker, int(MQTT_Port), int(Keep_Alive_Interval))

#Continue the network loop and close db connection
mqttc.loop_forever()
db.close()
print("MySQL connection is closed")

该虚拟服务器上安装了Moqit和mysql服务器的Mosquitto。首先，当我运行此脚本时，将收集来自MQTT Broker的所有数据并将其存储到mysql数据库中。它在一整天内正常工作。第二天，没有做任何更改，我将数据发送到了MQTT经纪人。数据是由paho mqtt客户端收集的，但无法将其存储在mysql数据库中。错误和输出如下：

('Connected to MySQL Server version ', '5.7.30-0ubuntu0.18.04.1')
subscribed
Insert from MQTT
wait
my/publish/topic 0 acc, 10245, tyu
Record inserted successfully into gnss table
Insert from MQTT
wait
my/publish/topic 0 hello world
Record inserted successfully into gnss table
Insert from MQTT
wait
my/publish/topic 0 hello world
Record inserted successfully into gnss table
Insert from MQTT
wait
my/publish/topic 0 new test
Record inserted successfully into gnss table
Insert from MQTT
wait
my/publish/topic 0 19/05/2020
Insert from MQTT
wait
my/publish/topic 0 19/05/2020
Insert from MQTT
wait
my/publish/topic 0 Tuesday
Insert from MQTT
wait
my/publish/topic 0 Tuesday
Traceback (most recent call last):
  File "mqtt.py", line 8, in <module>
    db='nrf91')
  File "/home/ubuntu/.local/lib/python2.7/site-packages/mysql/connector/__init__.py", line 264, in connect
    return CMySQLConnection(*args, **kwargs)
  File "/home/ubuntu/.local/lib/python2.7/site-packages/mysql/connector/connection_cext.py", line 80, in __init__
    self.connect(**kwargs)
  File "/home/ubuntu/.local/lib/python2.7/site-packages/mysql/connector/abstracts.py", line 960, in connect
    self._open_connection()
  File "/home/ubuntu/.local/lib/python2.7/site-packages/mysql/connector/connection_cext.py", line 219, in _open_connection
    sqlstate=exc.sqlstate)
mysql.connector.errors.DatabaseError: 2003 (HY000): Can't connect to MySQL server on '3.XX.XXX.89' (110)

我收到此mysql连接器数据库错误。如何解决这个错误？最初有与mysql服务器的连接，但第二天它就消失了。那么如何在不引起此错误的情况下始终保持与mysql服务器的连接呢？