consumer抓取消息--一个线程抓取,N个consumer的n个线程消费

启动流程:

consumer将自己注册.

每个consumer都有一个pullMessageSrvice,启动线程接受pullReques.

第一个pullReuqest是balanceService里发出的.

RequestCode.pull_message

最终汇总到pullAPIWrapper.pullKernelImpl去请求 ?

为什么说拉数据都是在一个线程里拉取的,不是很懂?

消费数据是每个consumer都有N个线程,在最外层的consumer DefaultMQPushConsumer(主要配置对应配置)里. 封装了真正的DefaultMQPushConsumerImpl实现类.

每个消费者实例都有消费线程,可配置订阅哪些topic. N个消费者实例最终都对应一个MQClientInstance (原因,clientId都是默认值)

  public MQClientInstance getAndCreateMQClientInstance(final ClientConfig clientConfig, RPCHook rpcHook) {
        String clientId = clientConfig.buildMQClientId();
        MQClientInstance instance = this.factoryTable.get(clientId);
        if (null == instance) {
            instance =
                    new MQClientInstance(clientConfig.cloneClientConfig(),
                            this.factoryIndexGenerator.getAndIncrement(), clientId, rpcHook);
            MQClientInstance prev = this.factoryTable.putIfAbsent(clientId, instance);
            if (prev != null) {
                instance = prev;
            } else {
                // TODO log
            }
        }

        return instance;
    }

 this.mQClientFactory =
                        MQClientManager.getInstance().getAndCreateMQClientInstance(this.defaultMQPullConsumer,
                                this.rpcHook);