NameServer是一个注册中心，Broker在启动时向所有的NameServer注册，生产者Producer和消费者Consumer可以从NameServer中获取所有注册的Broker列表，并从中选取Broker进行消息的发送和消费。
NameServer的启动类是NamesrvStartup，主要做了两件事情：
- 调用
createNamesrvController方法创建NamesrvController，NamesrvController是NameServer的核心 - 调用start方法，启动NameServer
public class NamesrvStartup {
private static InternalLogger log;
private static Properties properties = null;
private static CommandLine commandLine = null;
public static void main(String[] args) {
// 启动入口
main0(args);
}
public static NamesrvController main0(String[] args) {
try {
// 创建NamesrvController
NamesrvController controller = createNamesrvController(args);
// 启动nameserver
start(controller);
String tip = "The Name Server boot success. serializeType=" + RemotingCommand.getSerializeTypeConfigInThisServer();
log.info(tip);
System.out.printf("%s%n", tip);
return controller;
} catch (Throwable e) {
e.printStackTrace();
System.exit(-1);
}
return null;
}
}
创建NamesrvController
createNamesrvController方法主要是对配置信息进行处理：
- 创建
NamesrvConfig，从名字可以看出是记录NameServer的相关配置信息 - 创建
NettyServerConfig，与Netty服务相关的配置信息，默认设置监听端口为9876 - 从启动命令中检查是否通过
- c指定了配置文件，如果指定了配置文件，从指定的路径中加载文件，并将解析文件将配置保存到NamesrvConfig和NettyServerConfig中 - 校验RocketMQ的主目录是否为空，可以在启动命令中通过
-Drocketmq.home.dir=路径指定主目录，也可以在操作系统设置环境变量ROCKETMQ_HOME的方式来指定 - 处理日志相关的设置
- 创建
NamesrvController并返回
public class NamesrvStartup {
public static NamesrvController createNamesrvController(String[] args) throws IOException, JoranException {
System.setProperty(RemotingCommand.REMOTING_VERSION_KEY, Integer.toString(MQVersion.CURRENT_VERSION));
Options options = ServerUtil.buildCommandlineOptions(new Options());
commandLine = ServerUtil.parseCmdLine("mqnamesrv", args, buildCommandlineOptions(options), new PosixParser());
if (null == commandLine) {
System.exit(-1);
return null;
}
// Nameserver相关配置
final NamesrvConfig namesrvConfig = new NamesrvConfig();
// Netty服务器连接相关配置
final NettyServerConfig nettyServerConfig = new NettyServerConfig();
// 设置端口
nettyServerConfig.setListenPort(9876);
// 如果启动命令中指定了配置文件
if (commandLine.hasOption('c')) {
String file = commandLine.getOptionValue('c');
if (file != null) {
// 获取文件
InputStream in = new BufferedInputStream(new FileInputStream(file));
properties = new Properties();
properties.load(in);
// 解析配置文件
MixAll.properties2Object(properties, namesrvConfig);
MixAll.properties2Object(properties, nettyServerConfig);
namesrvConfig.setConfigStorePath(file);
System.out.printf("load config properties file OK, %s%n", file);
in.close();
}
}
// 如果启动命令中带了-p参数,打印NameServer的相关配置信息
if (commandLine.hasOption('p')) {
InternalLogger console = InternalLoggerFactory.getLogger(LoggerName.NAMESRV_CONSOLE_NAME);
MixAll.printObjectProperties(console, namesrvConfig);
MixAll.printObjectProperties(console, nettyServerConfig);
System.exit(0);
}
// 将启动命令中的一些设置记录到namesrvConfig
MixAll.properties2Object(ServerUtil.commandLine2Properties(commandLine), namesrvConfig);
// 如果RocketMQ主目录获取为空，打印异常信息
if (null == namesrvConfig.getRocketmqHome()) {
System.out.printf("Please set the %s variable in your environment to match the location of the RocketMQ installation%n", MixAll.ROCKETMQ_HOME_ENV);
System.exit(-2);
}
// 日志相关设置
LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory();
JoranConfigurator configurator = new JoranConfigurator();
configurator.setContext(lc);
lc.reset();
configurator.doConfigure(namesrvConfig.getRocketmqHome() + "/conf/logback_namesrv.xml");
log = InternalLoggerFactory.getLogger(LoggerName.NAMESRV_LOGGER_NAME);
MixAll.printObjectProperties(log, namesrvConfig);
MixAll.printObjectProperties(log, nettyServerConfig);
// 创建NamesrvController
final NamesrvController controller = new NamesrvController(namesrvConfig, nettyServerConfig);
controller.getConfiguration().registerConfig(properties);
return controller;
}
}
启动NameServer
NameServer的启动主要通过NamesrvController进行，处理逻辑如下：
- 调用NamesrvController的
initialize函数进行初始化 - 注册JVM关闭钩子函数，在JVM关闭的时候，调用NamesrvController的
shutdown方法关闭相关资源 - 调用NamesrvController的
start方法启动NameServer
public class NamesrvStartup {
public static NamesrvController start(final NamesrvController controller) throws Exception {
if (null == controller) {
throw new IllegalArgumentException("NamesrvController is null");
}
// 初始化NamesrvController
boolean initResult = controller.initialize();
if (!initResult) {
controller.shutdown();
System.exit(-3);
}
// 注册JVM关闭钩子函数
Runtime.getRuntime().addShutdownHook(new ShutdownHookThread(log, new Callable<Void>() {
@Override
public Void call() throws Exception {
controller.shutdown();
return null;
}
}));
// 启动nameserver
controller.start();
return controller;
}
}
NamesrvController
初始化
NamesrvController的初始化方法中主要做了如下操作：
- 加载配置信息，主要是从kvConfig.json中加载数据
- 创建NettyRemotingServer，用于网络通信
- 根据设置的工作线程数量创建netty服务相关线程池
- 注册处理器
DefaultRequestProcessor，用于处理收到的请求，比如Broker发起的注册请求 - 注册用于心跳检测的定时任务，定时扫描处于不活跃状态的Broker并剔除
- 注册定时打印KV信息的任务
public class NamesrvController {
private static final InternalLogger log = InternalLoggerFactory.getLogger(LoggerName.NAMESRV_LOGGER_NAME);
private final NamesrvConfig namesrvConfig; // NameServer相关配置
private final NettyServerConfig nettyServerConfig; // Netty服务相关配置
private final ScheduledExecutorService scheduledExecutorService = Executors.newSingleThreadScheduledExecutor(new ThreadFactoryImpl(
"NSScheduledThread")); // 定时执行任务的线程池
private final KVConfigManager kvConfigManager;
private final RouteInfoManager routeInfoManager; // 路由表
private RemotingServer remotingServer; // 远程服务，使用的是NettyRemotingServer
private BrokerHousekeepingService brokerHousekeepingService;
private ExecutorService remotingExecutor; // Netty服务相关线程池
// ...
public boolean initialize() {
// 加载配置信息
this.kvConfigManager.load();
// 创建NettyRemotingServer
this.remotingServer = new NettyRemotingServer(this.nettyServerConfig, this.brokerHousekeepingService);
// 创建netty服务相关线程池
this.remotingExecutor =
Executors.newFixedThreadPool(nettyServerConfig.getServerWorkerThreads(), new ThreadFactoryImpl("RemotingExecutorThread_"));
// 注册处理器
this.registerProcessor();
// 定时任务，扫描Broker
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
// 心跳监测扫描处于不活跃状态的Broker
NamesrvController.this.routeInfoManager.scanNotActiveBroker();
}
}, 5, 10, TimeUnit.SECONDS);
// 定时打印KV配置信息
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
NamesrvController.this.kvConfigManager.printAllPeriodically();
}
}, 1, 10, TimeUnit.MINUTES);
// ....
return true;
}
// 注册处理器
private void registerProcessor() {
if (namesrvConfig.isClusterTest()) {
this.remotingServer.registerDefaultProcessor(new ClusterTestRequestProcessor(this, namesrvConfig.getProductEnvName()),
this.remotingExecutor);
} else {
// 注册DefaultRequestProcessor处理请求
this.remotingServer.registerDefaultProcessor(new DefaultRequestProcessor(this), this.remotingExecutor);
}
}
}
启动
在启动方法中，主要是调用了RemotingServer的start方法启动服务，在NamesrvController的初始化方法中可知，使用的实现类是NettyRemotingServer，所以之后会启动Netty服务：
public void start() throws Exception {
// 启动Netty服务
this.remotingServer.start();
if (this.fileWatchService != null) {
this.fileWatchService.start();
}
}
Netty启动
NettyRemotingServer的start方法中主要是对Netty的一些设置，然后绑定端口并启动服务：
public class NettyRemotingServer extends NettyRemotingAbstract implements RemotingServer {
@Override
public void start() {
// ...
prepareSharableHandlers();
// Netty相关设置
ServerBootstrap childHandler =
this.serverBootstrap.group(this.eventLoopGroupBoss, this.eventLoopGroupSelector) // 设置EventLoopGroup线程组
.channel(useEpoll() ? EpollServerSocketChannel.class : NioServerSocketChannel.class) // 设置channel类型
.option(ChannelOption.SO_BACKLOG, nettyServerConfig.getServerSocketBacklog())
.option(ChannelOption.SO_REUSEADDR, true)
.option(ChannelOption.SO_KEEPALIVE, false)
.childOption(ChannelOption.TCP_NODELAY, true)
.localAddress(new InetSocketAddress(this.nettyServerConfig.getListenPort())) // 设置端口
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception { // 设置ChannelHandler
ch.pipeline()
.addLast(defaultEventExecutorGroup, HANDSHAKE_HANDLER_NAME, handshakeHandler)
.addLast(defaultEventExecutorGroup,
encoder,
new NettyDecoder(),
new IdleStateHandler(0, 0, nettyServerConfig.getServerChannelMaxIdleTimeSeconds()),
connectionManageHandler,
serverHandler
);
}
});
if (nettyServerConfig.getServerSocketSndBufSize() > 0) {
log.info("server set SO_SNDBUF to {}", nettyServerConfig.getServerSocketSndBufSize());
// 设置Socket发送缓存区大小
childHandler.childOption(ChannelOption.SO_SNDBUF, nettyServerConfig.getServerSocketSndBufSize());
}
if (nettyServerConfig.getServerSocketRcvBufSize() > 0) {
log.info("server set SO_RCVBUF to {}", nettyServerConfig.getServerSocketRcvBufSize());
// 设置Socket接收缓存区大小
childHandler.childOption(ChannelOption.SO_RCVBUF, nettyServerConfig.getServerSocketRcvBufSize());
}
if (nettyServerConfig.getWriteBufferLowWaterMark() > 0 && nettyServerConfig.getWriteBufferHighWaterMark() > 0) {
log.info("server set netty WRITE_BUFFER_WATER_MARK to {},{}",
nettyServerConfig.getWriteBufferLowWaterMark(), nettyServerConfig.getWriteBufferHighWaterMark());
childHandler.childOption(ChannelOption.WRITE_BUFFER_WATER_MARK, new WriteBufferWaterMark(
nettyServerConfig.getWriteBufferLowWaterMark(), nettyServerConfig.getWriteBufferHighWaterMark()));
}
if (nettyServerConfig.isServerPooledByteBufAllocatorEnable()) {
childHandler.childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT);
}
try {
// 绑定端口并启动服务
ChannelFuture sync = this.serverBootstrap.bind().sync();
InetSocketAddress addr = (InetSocketAddress) sync.channel().localAddress();
this.port = addr.getPort();
} catch (InterruptedException e1) {
throw new RuntimeException("this.serverBootstrap.bind().sync() InterruptedException", e1);
}
if (this.channelEventListener != null) {
this.nettyEventExecutor.start();
}
this.timer.scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
try {
NettyRemotingServer.this.scanResponseTable();
} catch (Throwable e) {
log.error("scanResponseTable exception", e);
}
}
}, 1000 * 3, 1000);
}
}
参考
丁威、周继锋《RocketMQ技术内幕》
RocketMQ版本：4.9.3
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文章来源: 博客园
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