eclipse mqttclient 性能&MQTT(32202): 正在发布过多的消息

摘要：性能正在发布过多的消息系统性能，注意请使用单线程的万条毫秒万条毫秒万毫秒万条毫秒多线程的正在发布过多的消息问题异常信息正在进行过多的发布解决办法消息发送发送限流用多带带的一个线程来完成消息的推送不用这个，使用就没有事增加的值反思笔者出现这个错

org.eclipse.paho.client.mqttv3

2.2 GHz Intel Core i7 mac系统

publish性能，注意请使用单线程的 mqttclinet

1万条 341毫秒
4万条 1163毫秒
5万 1450毫秒
10万条 2700毫秒

多线程的 mqttclinet MQTT(32202): 正在发布过多的消息 问题

[15:07:21]: publish failed, message: aaaa
正在进行过多的发布 (32202)
 at org.eclipse.paho.client.mqttv3.internal.ClientState.send(ClientState.java:496)
 at org.eclipse.paho.client.mqttv3.internal.ClientComms.internalSend(ClientComms.java:132)
 at org.eclipse.paho.client.mqttv3.internal.ClientComms.sendNoWait(ClientComms.java:156)
 at org.eclipse.paho.client.mqttv3.MqttAsyncClient.publish(MqttAsyncClient.java:1027)
 at org.eclipse.paho.client.mqttv3.MqttClient.publish(MqttClient.java:399)
 at io.communet.ichater.emq.util.MqttUtil.publishMsg(MqttUtil.java:171)
 at io.communet.ichater.emq.util.MqttUtil.publishMsg(MqttUtil.java:161)
 at io.communet.ichater.emq.sub.MqttSendMsgEventSubscribe.onEvent(MqttSendMsgEventSubscribe.java:28)
 at java.lang.reflect.Method.invoke(Native Method)
 at java.lang.reflect.Method.invoke(Method.java:372)
 at org.greenrobot.eventbus.EventBus.invokeSubscriber(EventBus.java:507)
 at org.greenrobot.eventbus.EventBus.invokeSubscriber(EventBus.java:501)
 at org.greenrobot.eventbus.AsyncPoster.run(AsyncPoster.java:46)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
 at java.lang.Thread.run(Thread.java:818)

消息发送发送限流

用多带带的一个线程来完成 MQ 消息的推送 (不用这个MqttAsyncClient ，使用MqttClient 就没有事)

options.setMaxInflight(1000) 增加 actualInFlight 的值;

笔者出现这个错误是因为使用 EventBus, 之前使用多带带线程的 Handler 是没有问题的, 调查发现, 使用 EventBus 是新建线程运行的, 而 Handler 是多带带一个线程.
所以当发送大量消息的时候, EventBus 几乎是同一个点发出去, 就会造成这个错误

根据堆栈信息找到报错地方

if (actualInFlight >= this.maxInflight) {
    //@TRACE 613= sending {0} msgs at max inflight window
    log.fine(CLASS_NAME, methodName, "613", new Object[]{new Integer(actualInFlight)});

    throw new MqttException(MqttException.REASON_CODE_MAX_INFLIGHT);
}

其中 actualInFlight 如下

// processed until the inflight window has space. 
if (actualInFlight < this.maxInflight) {
    // The in flight window is not full so process the 
    // first message in the queue
    result = (MqttWireMessage)pendingMessages.elementAt(0);
    pendingMessages.removeElementAt(0);
    actualInFlight++;
    
    //@TRACE 623=+1 actualInFlight={0}
    log.fine(CLASS_NAME,methodName,"623",new Object[]{new Integer(actualInFlight)});
}

从 pendingMessages 中取出消息时, actualInFlight 加 1, maxInflight 可以自己设定, 默认值为 10.

public class ClientState {
  ...
  volatile private Vector pendingMessages;
  ...
}

在 ClientState 中：

public void send(MqttWireMessage message, MqttToken token) throws MqttException {
        ... 
        if (message instanceof MqttPublish) {
            synchronized (queueLock) {
                if (actualInFlight >= this.maxInflight) {
                    //@TRACE 613= sending {0} msgs at max inflight window
                    log.fine(CLASS_NAME, methodName, "613", new Object[]{new Integer(actualInFlight)});

                    throw new MqttException(MqttException.REASON_CODE_MAX_INFLIGHT);
                }
                
                MqttMessage innerMessage = ((MqttPublish) message).getMessage();
                //@TRACE 628=pending publish key={0} qos={1} message={2}
                log.fine(CLASS_NAME,methodName,"628", new Object[]{new Integer(message.getMessageId()), new Integer(innerMessage.getQos()), message});

                switch(innerMessage.getQos()) {
                    case 2:
                        outboundQoS2.put(new Integer(message.getMessageId()), message);
                        persistence.put(getSendPersistenceKey(message), (MqttPublish) message);
                        break;
                    case 1:
                        outboundQoS1.put(new Integer(message.getMessageId()), message);
                        persistence.put(getSendPersistenceKey(message), (MqttPublish) message);
                        break;
                }
                tokenStore.saveToken(token, message);
                pendingMessages.addElement(message);
                queueLock.notifyAll();
            }
        } else {
        ...
        }
    }

可以看到 pendingMessages 中添加元素的时候并没有做 qos 类型的判断

private void decrementInFlight() {
    final String methodName = "decrementInFlight";
    synchronized (queueLock) {
        actualInFlight--;
        //@TRACE 646=-1 actualInFlight={0}
        log.fine(CLASS_NAME,methodName,"646",new Object[]{new Integer(actualInFlight)});
            
        if (!checkQuiesceLock()) {
            queueLock.notifyAll();
        }
    }
}

当收到消息反馈时 actualInFlight 减 1.