如何在计划的后台线程中传输MQTT消息？

如何解决如何在计划的后台线程中传输MQTT消息？

我已成功运行基于MQTT的应用程序。

随着时间的流逝，我迁移了SW组件版本和我将MQTT消息传输移至APScheduler后台线程中。客户端实例通过依赖项注入传递到作业调度。

现在我正在使用mosquitto eclipse mqtt代理docker镜像eclipse-mosquitto:1.6.10和Python paho客户端paho-mqtt = "1.5.0"。

现在，如果我尝试与客户端连接到代理，则连接断开，并且收到错误Connection Refused: unacceptable protocol version.，该错误抛出in the v1.5 client source code。

客户端连接如下：

def on_disconnect(client,userdata,rc):  # pylint: disable=invalid-name,unused-argument
    print(mqtt.connack_string(rc))

client = mqtt.Client(
    client_id="mvp-end-device-agent",clean_session=False,protocol=mqtt.MQTTv311,)
client.on_disconnect = on_disconnect
user = "mvp-end-device-agent"
pwd = "some-string"
client.username_pw_set(user,pwd)
client.connect(host,port)  # implicit timeout of 60 seconds

    def on_disconnect(client,unused-argument

mosquitto/config/acl应该仍然匹配：

user mvp-end-device-agent
topic write ...

以及mosquitto/config/passwd配置：

mvp-end-device-agent:<HASHEDPWD>

和mosquitto/config/mosquitto.conf配置：

password_file /mosquitto/config/passwd
acl_file /mosquitto/config/acls

最可能相关的日志条目（mqtt-explorer-31e2d891用于调试，mvp-end-device-agent是实际的客户端）：

1603891749: New connection from 172.18.0.6 on port 1883.
1603891749: New client connected from 172.18.0.6 as mvp-end-device-agent (p2,c0,k1,u'mvp-end-device-agent').
1603891749: No will message specified.
1603891749: Sending CONNACK to mvp-end-device-agent (1,0)
1603891750: Received PINGREQ from mqtt-explorer-31e2d891
1603891750: Sending PINGRESP to mqtt-explorer-31e2d891
1603891751: Received PINGREQ from mvp-end-device-agent
1603891751: Sending PINGRESP to mvp-end-device-agent
1603891752: Received PINGREQ from mvp-end-device-agent
1603891752: Sending PINGRESP to mvp-end-device-agent
1603891753: Received PINGREQ from mvp-end-device-agent
1603891753: Sending PINGRESP to mvp-end-device-agent
1603891754: Received PINGREQ from mvp-end-device-agent
1603891754: Sending PINGRESP to mvp-end-device-agent
1603891755: Received PINGREQ from mvp-end-device-agent
1603891755: Sending PINGRESP to mvp-end-device-agent
1603891755: Received DISCONNECT from mvp-end-device-agent
1603891755: Client mvp-end-device-agent disconnected.

我很难弄清这个问题的根本原因。引发此错误的潜在原因是什么？

编辑：我通过依赖注入将mqtt客户端传递给APScheduler作业，以计划发送MQTT消息，作为作业执行的一部分。每个作业都在线程中执行。事实证明，Connection Refused: unacceptable protocol version.的根本原因是在执行线程后，客户端被隐式断开，这完全合乎情理。