找到org.apache.rocketmq.broker.BrokerStartup启动类的main方法
public static void main(String[] args) {
start(createBrokerController(args));
}
找到org.apache.rocketmq.broker.BrokerStartup#createBrokerController方法下的这几行代码
final BrokerController controller = new BrokerController(
brokerConfig,
nettyServerConfig,
nettyClientConfig,
messageStoreConfig);
// remember all configs to prevent discard
controller.getConfiguration().registerConfig(properties);
//看着一行代码controller.initialize()初始化方法
boolean initResult = controller.initialize();
if (!initResult) {
controller.shutdown();
System.exit(-3);
}
找到controller.initialize() , 进入 org.apache.rocketmq.broker.BrokerController#initialize方法找到下面的代码
this.consumerManageExecutor =
Executors.newFixedThreadPool(this.brokerConfig.getConsumerManageThreadPoolNums(), new ThreadFactoryImpl(
"ConsumerManageThread_"));
//调用registerProcessor()
this.registerProcessor();
final long initialDelay = UtilAll.computeNextMorningTimeMillis() - System.currentTimeMillis();
final long period = 1000 * 60 * 60 * 24;
跟着进入this.registerProcessor()方法
org.apache.rocketmq.broker.BrokerController#registerProcessor
/**
* ClientManageProcessor
*/
ClientManageProcessor clientProcessor = new ClientManageProcessor(this);
找到ClientManageProcessor 类, 看到 processRequest 方法
进入org.apache.rocketmq.broker.processor.ClientManageProcessor#processRequest
@Override
public RemotingCommand processRequest(ChannelHandlerContext ctx, RemotingCommand request)
throws RemotingCommandException {
switch (request.getCode()) {
case RequestCode.HEART_BEAT:
return this.heartBeat(ctx, request);
case RequestCode.UNREGISTER_CLIENT:
return this.unregisterClient(ctx, request);
case RequestCode.CHECK_CLIENT_CONFIG:
return this.checkClientConfig(ctx, request);
default:
break;
}
return null;
}
找到 this.heartBeat(ctx, request) 方法是broker发送心跳包的方法 ,看到下面这行代码
boolean changed = this.brokerController.getConsumerManager().registerConsumer(
data.getGroupName(),
clientChannelInfo,
data.getConsumeType(),
data.getMessageModel(),
data.getConsumeFromWhere(),
data.getSubscriptionDataSet(),
isNotifyConsumerIdsChangedEnable
);
进入这个org.apache.rocketmq.broker.client.ConsumerManager#registerConsumer方法
public boolean registerConsumer(final String group, final ClientChannelInfo clientChannelInfo,
ConsumeType consumeType, MessageModel messageModel, ConsumeFromWhere consumeFromWhere,
final Set<SubscriptionData> subList, boolean isNotifyConsumerIdsChangedEnable) {
ConsumerGroupInfo consumerGroupInfo = this.consumerTable.get(group);
if (null == consumerGroupInfo) {
ConsumerGroupInfo tmp = new ConsumerGroupInfo(group, consumeType, messageModel, consumeFromWhere);
ConsumerGroupInfo prev = this.consumerTable.putIfAbsent(group, tmp);
consumerGroupInfo = prev != null ? prev : tmp;
}
boolean r1 =
consumerGroupInfo.updateChannel(clientChannelInfo, consumeType, messageModel,
consumeFromWhere);
boolean r2 = consumerGroupInfo.updateSubscription(subList);
if (r1 || r2) {
if (isNotifyConsumerIdsChangedEnable) {
//监听消费者改变的方法
this.consumerIdsChangeListener.handle(ConsumerGroupEvent.CHANGE, group, consumerGroupInfo.getAllChannel());
}
}
this.consumerIdsChangeListener.handle(ConsumerGroupEvent.REGISTER, group, subList);
return r1 || r2;
}
this.consumerIdsChangeListener.handle(ConsumerGroupEvent.CHANGE, group, consumerGroupInfo.getAllChannel());
进入这个handel方法里面
public void handle(ConsumerGroupEvent event, String group, Object... args) {
if (event == null) {
return;
}
switch (event) {
case CHANGE:
if (args == null || args.length < 1) {
return;
}
List<Channel> channels = (List<Channel>) args[0];
if (channels != null && brokerController.getBrokerConfig().isNotifyConsumerIdsChangedEnable()) {
for (Channel chl : channels) {
this.brokerController.getBroker2Client().notifyConsumerIdsChanged(chl, group);
}
}
break;
case UNREGISTER:
this.brokerController.getConsumerFilterManager().unRegister(group);
break;
case REGISTER:
if (args == null || args.length < 1) {
return;
}
Collection<SubscriptionData> subscriptionDataList = (Collection<SubscriptionData>) args[0];
this.brokerController.getConsumerFilterManager().register(group, subscriptionDataList);
break;
default:
throw new RuntimeException("Unknown event " + event);
}
}
然后进入this.brokerController.getBroker2Client().notifyConsumerIdsChanged(chl, group) 方法里
org.apache.rocketmq.broker.client.net.Broker2Client#notifyConsumerIdsChanged
public void notifyConsumerIdsChanged(
final Channel channel,
final String consumerGroup) {
if (null == consumerGroup) {
log.error("notifyConsumerIdsChanged consumerGroup is null");
return;
}
NotifyConsumerIdsChangedRequestHeader requestHeader = new NotifyConsumerIdsChangedRequestHeader();
requestHeader.setConsumerGroup(consumerGroup);
RemotingCommand request =
RemotingCommand.createRequestCommand(RequestCode.NOTIFY_CONSUMER_IDS_CHANGED, requestHeader);
try {
this.brokerController.getRemotingServer().invokeOneway(channel, request, 10);
} catch (Exception e) {
log.error("notifyConsumerIdsChanged exception. group={}, error={}", consumerGroup, e.toString());
}
}
发送RequestCode.NOTIFY_CONSUMER_IDS_CHANGED请求码
然后, 在消费者端监听这个请求码
org.apache.rocketmq.client.impl.ClientRemotingProcessor#processRequest
public RemotingCommand processRequest(ChannelHandlerContext ctx,
RemotingCommand request) throws RemotingCommandException {
switch (request.getCode()) {
case RequestCode.CHECK_TRANSACTION_STATE:
return this.checkTransactionState(ctx, request);
case RequestCode.NOTIFY_CONSUMER_IDS_CHANGED:
return this.notifyConsumerIdsChanged(ctx, request);
case RequestCode.RESET_CONSUMER_CLIENT_OFFSET:
return this.resetOffset(ctx, request);
case RequestCode.GET_CONSUMER_STATUS_FROM_CLIENT:
return this.getConsumeStatus(ctx, request);
case RequestCode.GET_CONSUMER_RUNNING_INFO:
return this.getConsumerRunningInfo(ctx, request);
case RequestCode.CONSUME_MESSAGE_DIRECTLY:
return this.consumeMessageDirectly(ctx, request);
case RequestCode.PUSH_REPLY_MESSAGE_TO_CLIENT:
return this.receiveReplyMessage(ctx, request);
default:
break;
}
return null;
}
消费者端匹配到请求码NOTIFY_CONSUMER_IDS_CHANGED, 调用this.notifyConsumerIdsChanged(ctx, request)方法
public RemotingCommand notifyConsumerIdsChanged(ChannelHandlerContext ctx,
RemotingCommand request) throws RemotingCommandException {
try {
final NotifyConsumerIdsChangedRequestHeader requestHeader =
(NotifyConsumerIdsChangedRequestHeader) request.decodeCommandCustomHeader(NotifyConsumerIdsChangedRequestHeader.class);
log.info("receive broker's notification[{}], the consumer group: {} changed, rebalance immediately",
RemotingHelper.parseChannelRemoteAddr(ctx.channel()),
requestHeader.getConsumerGroup());
this.mqClientFactory.rebalanceImmediately();
} catch (Exception e) {
log.error("notifyConsumerIdsChanged exception", RemotingHelper.exceptionSimpleDesc(e));
}
return null;
}
关键性的一行代码 this.mqClientFactory.rebalanceImmediately();
public void rebalanceImmediately() {
this.rebalanceService.wakeup();
}
立刻唤醒负载均衡的线程, 对消费者消费的消息队列重新 做负载均衡处理
RebalanceService 是一个线程,默认等待20秒自动重做负载均衡
public class RebalanceService extends ServiceThread {
private static long waitInterval =
Long.parseLong(System.getProperty(
"rocketmq.client.rebalance.waitInterval", "20000"));
private final InternalLogger log = ClientLogger.getLog();
private final MQClientInstance mqClientFactory;
public RebalanceService(MQClientInstance mqClientFactory) {
this.mqClientFactory = mqClientFactory;
}
@Override
public void run() {
log.info(this.getServiceName() + " service started");
while (!this.isStopped()) {
//默认等待20秒,如果调用了wakeup方法,立刻唤醒线程执行
this.waitForRunning(waitInterval);
this.mqClientFactory.doRebalance();
}
log.info(this.getServiceName() + " service end");
}
@Override
public String getServiceName() {
return RebalanceService.class.getSimpleName();
}
}
