聊聊rocketmq的adjustThreadPoolNumsThreshold

序

本文主要研究一下rocketmq的adjustThreadPoolNumsThreshold

DefaultMQPushConsumer

rocketmq-client-4.5.2-sources.jar!/org/apache/rocketmq/client/consumer/DefaultMQPushConsumer.java

代码语言：javascript复制

public class DefaultMQPushConsumer extends ClientConfig implements MQPushConsumer {

    private final InternalLogger log = ClientLogger.getLog();

    //......

    /**
     * Threshold for dynamic adjustment of the number of thread pool
     */
    private long adjustThreadPoolNumsThreshold = 100000;

    public long getAdjustThreadPoolNumsThreshold() {
        return adjustThreadPoolNumsThreshold;
    }

    public void setAdjustThreadPoolNumsThreshold(long adjustThreadPoolNumsThreshold) {
        this.adjustThreadPoolNumsThreshold = adjustThreadPoolNumsThreshold;
    }

    //......
}

• DefaultMQPushConsumer定义了adjustThreadPoolNumsThreshold属性，默认为100000

DefaultMQPushConsumerImpl

ocketmq-client-4.5.2-sources.jar!/org/apache/rocketmq/client/impl/consumer/DefaultMQPushConsumerImpl.java

代码语言：javascript复制

public class DefaultMQPushConsumerImpl implements MQConsumerInner {

//......

    public void adjustThreadPool() {
        long computeAccTotal = this.computeAccumulationTotal();
        long adjustThreadPoolNumsThreshold = this.defaultMQPushConsumer.getAdjustThreadPoolNumsThreshold();

        long incThreshold = (long) (adjustThreadPoolNumsThreshold * 1.0);

        long decThreshold = (long) (adjustThreadPoolNumsThreshold * 0.8);

        if (computeAccTotal >= incThreshold) {
            this.consumeMessageService.incCorePoolSize();
        }

        if (computeAccTotal < decThreshold) {
            this.consumeMessageService.decCorePoolSize();
        }
    }

    private long computeAccumulationTotal() {
        long msgAccTotal = 0;
        ConcurrentMap<MessageQueue, ProcessQueue> processQueueTable = this.rebalanceImpl.getProcessQueueTable();
        Iterator<Entry<MessageQueue, ProcessQueue>> it = processQueueTable.entrySet().iterator();
        while (it.hasNext()) {
            Entry<MessageQueue, ProcessQueue> next = it.next();
            ProcessQueue value = next.getValue();
            msgAccTotal  = value.getMsgAccCnt();
        }

        return msgAccTotal;
    }

    //......
}

• adjustThreadPool方法会计算computeAccTotal，然后使用adjustThreadPoolNumsThreshold * 1.0作为incThreshold，使用adjustThreadPoolNumsThreshold * 0.8作为decThreshold；对于computeAccTotal大于等于incThreshold的，执行consumeMessageService.incCorePoolSize()；对于computeAccTotal小于decThreshold的执行consumeMessageService.decCorePoolSize()

MQClientInstance

rocketmq-client-4.5.2-sources.jar!/org/apache/rocketmq/client/impl/factory/MQClientInstance.java

代码语言：javascript复制

public class MQClientInstance {
//......

    public void start() throws MQClientException {

        synchronized (this) {
            switch (this.serviceState) {
                case CREATE_JUST:
                    this.serviceState = ServiceState.START_FAILED;
                    // If not specified,looking address from name server
                    if (null == this.clientConfig.getNamesrvAddr()) {
                        this.mQClientAPIImpl.fetchNameServerAddr();
                    }
                    // Start request-response channel
                    this.mQClientAPIImpl.start();
                    // Start various schedule tasks
                    this.startScheduledTask();
                    // Start pull service
                    this.pullMessageService.start();
                    // Start rebalance service
                    this.rebalanceService.start();
                    // Start push service
                    this.defaultMQProducer.getDefaultMQProducerImpl().start(false);
                    log.info("the client factory [{}] start OK", this.clientId);
                    this.serviceState = ServiceState.RUNNING;
                    break;
                case RUNNING:
                    break;
                case SHUTDOWN_ALREADY:
                    break;
                case START_FAILED:
                    throw new MQClientException("The Factory object["   this.getClientId()   "] has been created before, and failed.", null);
                default:
                    break;
            }
        }
    }

    private void startScheduledTask() {

        //......

        this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {

            @Override
            public void run() {
                try {
                    MQClientInstance.this.adjustThreadPool();
                } catch (Exception e) {
                    log.error("ScheduledTask adjustThreadPool exception", e);
                }
            }
        }, 1, 1, TimeUnit.MINUTES);
    }

    public void adjustThreadPool() {
        Iterator<Entry<String, MQConsumerInner>> it = this.consumerTable.entrySet().iterator();
        while (it.hasNext()) {
            Entry<String, MQConsumerInner> entry = it.next();
            MQConsumerInner impl = entry.getValue();
            if (impl != null) {
                try {
                    if (impl instanceof DefaultMQPushConsumerImpl) {
                        DefaultMQPushConsumerImpl dmq = (DefaultMQPushConsumerImpl) impl;
                        dmq.adjustThreadPool();
                    }
                } catch (Exception e) {
                }
            }
        }
    }

//......
}

• MQClientInstance的start方法对于CREATE_JUST状态会执行startScheduledTask()方法，后者会注册一个定时任务，每隔1分钟执行一次adjustThreadPool方法；adjustThreadPool方法则遍历consumerTable的MQConsumerInner，对于DefaultMQPushConsumerImpl类型的MQConsumerInner执行adjustThreadPool方法

小结

DefaultMQPushConsumer定义了adjustThreadPoolNumsThreshold属性，默认为100000；MQClientInstance的start方法对于CREATE_JUST状态会执行startScheduledTask()方法，后者会注册一个定时任务，每隔1分钟执行一次adjustThreadPool方法；adjustThreadPool方法则遍历consumerTable的MQConsumerInner，对于DefaultMQPushConsumerImpl类型的MQConsumerInner执行adjustThreadPool方法

doc

• DefaultMQPushConsumer

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