RocketMQ源码解析-Broker启动

以下源码基于Rocket MQ 4.7.0

1. Broker

消息中转角色，负责存储消息、转发消息。Broker在RocketMQ系统中负责接收从生产者发送来的消息并存储、同时为消费者的拉取请求作准备。代理服务器也存储消息相关的元数据，包括消费者组、消费进度偏移和主题和队列消息等。

2. Broker作用

主要四个作用：

• 消息存储
• 消息投递
• 消息查询
• 服务的高可用

这四个功能由五个模块来实现。

3. Broker启动流程分析

总体的启动流程和NameServer的启动流程差不多但是比NameServer的启动流程复杂：

这个流程大致分为以下的几个步骤：

1. BrokerController创建
   • NettyServer和NettyClient的配置处理
   • 命令行参数的处理
   • Broker角色的处理
   • 创建BrokerController
   • 初始化BrokerController通过调用方法
2. BrokerController启动

4. BrokerController创建

BrokerStartUp.createBrokerController 调用方法创建

上图是设置Netty的发送和接收缓冲区的大小。

上图主要是处理在集群条件小的Broker角色的，从这里看出来brokerId为0的为Mater节点，其他的为Slave节点。

角色类型：SYNC_MASTER/ASYNC_MASTER/SLAVE 默认为ASYNC_MASTER，

官方文档：https://rocketmq.apache.org/docs/rmq-deployment/

上图是处理命令行参数

初始化BrokerController。然后返回controller。

5. BrokerController启动

    public static BrokerController start(BrokerController controller) {
        try {

            controller.start();

            String tip = "The broker[" + controller.getBrokerConfig().getBrokerName() + ", "
                + controller.getBrokerAddr() + "] boot success. serializeType=" + RemotingCommand.getSerializeTypeConfigInThisServer();

            if (null != controller.getBrokerConfig().getNamesrvAddr()) {
                tip += " and name server is " + controller.getBrokerConfig().getNamesrvAddr();
            }

            log.info(tip);
            System.out.printf("%s%n", tip);
            return controller;
        } catch (Throwable e) {
            e.printStackTrace();
            System.exit(-1);
        }

        return null;
    }

启动比较简单，调用start方法。

6. Broker配置

Property Name	Default value	Details
listenPort	10911	listen port for client
namesrvAddr	null	name server address
brokerIP1	InetAddress for network interface	Should be configured if having multiple addresses
brokerName	null	broker name
brokerClusterName	DefaultCluster	this broker belongs to which cluster
brokerId	0	broker id, 0 means master, positive integers mean slave
storePathCommitLog	$HOME/store/commitlog/	file path for commit log
storePathConsumerQueue	$HOME/store/consumequeue/	file path for consume queue
mapedFileSizeCommitLog	1024 * 1024 * 1024(1G)	mapped file size for commit log
deleteWhen	04	When to delete the commitlog which is out of the reserve time
fileReserverdTime	72	The number of hours to keep a commitlog before deleting it
brokerRole	ASYNC_MASTER	SYNC_MASTER/ASYNC_MASTER/SLAVE
flushDiskType	ASYNC_FLUSH	{SYNC_FLUSH/ASYNC_FLUSH}. Broker of SYNC_FLUSH mode flushes each message onto disk before acknowledging producer. Broker of ASYNC_FLUSH mode, on the other hand, takes advantage of group-committing, achieving better performance.