摘要：性能正在發布過多的消息系統性能，注意請使用單線程的萬條毫秒萬條毫秒萬毫秒萬條毫秒多線程的正在發布過多的消息問題異常信息正在進行過多的發布解決辦法消息發送發送限流用多帶帶的一個線程來完成消息的推送不用這個，使用就沒有事增加的值反思筆者出現這個錯

org.eclipse.paho.client.mqttv3

2.2 GHz Intel Core i7 mac系統

publish性能，注意請使用單線程的 mqttclinet

1萬條 341毫秒
4萬條 1163毫秒
5萬 1450毫秒
10萬條 2700毫秒

多線程的 mqttclinet?MQTT(32202): 正在發布過多的消息 問題

[15:07:21]: publish failed, message: aaaa
正在進行過多的發布 (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)

消息發送發送限流

用多帶帶的一個線程來完成 MQ 消息的推送 (不用這個MqttAsyncClient ，使用MqttClient 就沒有事)

options.setMaxInflight(1000)?增加?actualInFlight?的值;

筆者出現這個錯誤是因為使用 EventBus, 之前使用多帶帶線程的 Handler 是沒有問題的, 調查發現, 使用 EventBus 是新建線程運行的, 而 Handler 是多帶帶一個線程.
所以當發送大量消息的時候, EventBus 幾乎是同一個點發出去, 就會造成這個錯誤

根據堆棧信息找到報錯地方

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)});
}

從?pendingMessages?中取出消息時,?actualInFlight?加 1,?maxInflight?可以自己設定, 默認值為 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?中添加元素的時候并沒有做?qos?類型的判斷

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();
        }
    }
}

當收到消息反饋時?actualInFlight?減 1.