1、首先找到NameServer启动的主类
该类在namesrv模块中，类全路径为org.apache.rocketmq.namesrv.NamesrvStartup，我们在启动NameServer的时候只需要运行该类就行了。
2、从main方法入口看NameServer启动都做了哪些事情？
public static void main(String[] args) {
main0(args);
}
首先调用了main0方法，接着进入main0方法：
public static NamesrvController main0(String[] args) {
try {
// 比较重要的方法
NamesrvController controller = createNamesrvController(args);
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;
}
2.1、调用createNamesrvController方法创建NamesrvController实例
createNamesrvController方法初始化了一个Nameserver控制器，主要负责NameServer的组件管理。进入createNamesrvController方法：
public static NamesrvController createNamesrvController(String[] args) throws IOException, JoranException {
System.setProperty(RemotingCommand.REMOTING_VERSION_KEY, Integer.toString(MQVersion.CURRENT_VERSION));
//PackageConflictDetect.detectFastjson();
Options options = ServerUtil.buildCommandlineOptions(new Options());
commandLine = ServerUtil.parseCmdLine("mqnamesrv", args, buildCommandlineOptions(options), new PosixParser());
if (null == commandLine) {
System.exit(-1);
return null;
}
final NamesrvConfig namesrvConfig = new NamesrvConfig();
final NettyServerConfig nettyServerConfig = new NettyServerConfig();
nettyServerConfig.setListenPort(9876);
// -c configFile 通过-c命令指定配置文件路径
if (commandLine.hasOption('c')) {
String file = commandLine.getOptionValue('c');
if (file != null) {
InputStream in = new BufferedInputStream(new FileInputStream(file));
properties = new Properties();
properties.load(in);
MixAll.properties2Object(properties, namesrvConfig);
MixAll.properties2Object(properties, nettyServerConfig);
namesrvConfig.setConfigStorePath(file);
System.out.printf("load config properties file OK, %s%n", file);
in.close();
}
}
if (commandLine.hasOption('p')) {
InternalLogger console = InternalLoggerFactory.getLogger(LoggerName.NAMESRV_CONSOLE_NAME);
MixAll.printObjectProperties(console, namesrvConfig);
MixAll.printObjectProperties(console, nettyServerConfig);
System.exit(0);
}
// args数组传入的参数前面封装到了commandLine对象中；args参数格式为 “--属性名 属性值”
// 如果以这种方式传入了参数，那么会将参数赋值给namesrvConfig对象上
MixAll.properties2Object(ServerUtil.commandLine2Properties(commandLine), namesrvConfig);
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);
}
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);
final NamesrvController controller = new NamesrvController(namesrvConfig, nettyServerConfig);
// remember all configs to prevent discard
controller.getConfiguration().registerConfig(properties);
return controller;
}
createNamesrvController方法主要做了几个事情：
1）、解析运行命令 “-c configFile”指定的文件属性配置，并赋值到NamesrvConfig和NettyServerConfig类的属性上；
2）、解析执行命令中是否有“-p”，有的话就打印从步骤1加载的属性配置
3）、解析args参数格式为“--属性名 属性值”并赋值到NamesrvConfig相应的属性上
4）、创建一个NamesrvController实例
NamesrvConfig、NettyServerConfig配置有哪些？
public class NamesrvConfig {
private static final InternalLogger log = InternalLoggerFactory.getLogger(LoggerName.NAMESRV_LOGGER_NAME);
// rocketmq主目录， 可以通过 -Drocketmq.home.dir=path设置
// 也可以通过环境变量ROCKETMQ_HOME来配置rocketmq主目录
private String rocketmqHome = System.getProperty(MixAll.ROCKETMQ_HOME_PROPERTY, System.getenv(MixAll.ROCKETMQ_HOME_ENV));
// NameServer存储KV配置属性的持久化路径
private String kvConfigPath = System.getProperty("user.home") + File.separator + "namesrv" + File.separator + "kvConfig.json";
// 默认配置文件路径，默认不生效。 如果要使用配置文件配置，需要使用-c选项
private String configStorePath = System.getProperty("user.home") + File.separator + "namesrv" + File.separator + "namesrv.properties";
private String productEnvName = "center";
private boolean clusterTest = false;
// 顺序消息启用开关，默认为false关闭
private boolean orderMessageEnable = false;
}
public class NettyServerConfig implements Cloneable {
private int listenPort = 8888;
private int serverWorkerThreads = 8;
private int serverCallbackExecutorThreads = 0;
private int serverSelectorThreads = 3;
private int serverOnewaySemaphoreValue = 256;
private int serverAsyncSemaphoreValue = 64;
private int serverChannelMaxIdleTimeSeconds = 120;
private int serverSocketSndBufSize = NettySystemConfig.socketSndbufSize;
private int serverSocketRcvBufSize = NettySystemConfig.socketRcvbufSize;
private boolean serverPooledByteBufAllocatorEnable = true;
/**
* make make install
*
*
* ../glibc-2.10.1/configure \ --prefix=/usr \ --with-headers=/usr/include \
* --host=x86_64-linux-gnu \ --build=x86_64-pc-linux-gnu \ --without-gd
*/
private boolean useEpollNativeSelector = false;
}
2.2、调用start方法执行初始化操作
public static NamesrvController start(final NamesrvController controller) throws Exception {
if (null == controller) {
throw new IllegalArgumentException("NamesrvController is null");
}
boolean initResult = controller.initialize();
if (!initResult) {
controller.shutdown();
System.exit(-3);
}
// 出错JVM狗子函数。
Runtime.getRuntime().addShutdownHook(new ShutdownHookThread(log, new Callable<Void>() {
@Override
public Void call() throws Exception {
controller.shutdown();
return null;
}
}));
controller.start();
return controller;
}
首先调用了NamesrvController#initialize方法进行初始化操作：
public boolean initialize() {
this.kvConfigManager.load();
this.remotingServer = new NettyRemotingServer(this.nettyServerConfig, this.brokerHousekeepingService);
this.remotingExecutor =
Executors.newFixedThreadPool(nettyServerConfig.getServerWorkerThreads(), new ThreadFactoryImpl("RemotingExecutorThread_"));
this.registerProcessor();
// 定时线程任务每隔十秒扫描一次Broker，移除处于不 激活状态的Broker
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
NamesrvController.this.routeInfoManager.scanNotActiveBroker();
}
}, 5, 10, TimeUnit.SECONDS);
// 定时线程每隔十分钟打印一次KV配置
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
NamesrvController.this.kvConfigManager.printAllPeriodically();
}
}, 1, 10, TimeUnit.MINUTES);
if (TlsSystemConfig.tlsMode != TlsMode.DISABLED) {
// Register a listener to reload SslContext
try {
fileWatchService = new FileWatchService(
new String[] {
TlsSystemConfig.tlsServerCertPath,
TlsSystemConfig.tlsServerKeyPath,
TlsSystemConfig.tlsServerTrustCertPath
},
new FileWatchService.Listener() {
boolean certChanged, keyChanged = false;
@Override
public void onChanged(String path) {
if (path.equals(TlsSystemConfig.tlsServerTrustCertPath)) {
log.info("The trust certificate changed, reload the ssl context");
reloadServerSslContext();
}
if (path.equals(TlsSystemConfig.tlsServerCertPath)) {
certChanged = true;
}
if (path.equals(TlsSystemConfig.tlsServerKeyPath)) {
keyChanged = true;
}
if (certChanged && keyChanged) {
log.info("The certificate and private key changed, reload the ssl context");
certChanged = keyChanged = false;
reloadServerSslContext();
}
}
private void reloadServerSslContext() {
((NettyRemotingServer) remotingServer).loadSslContext();
}
});
} catch (Exception e) {
log.warn("FileWatchService created error, can't load the certificate dynamically");
}
}
return true;
}
然后在调用NamesrvController#start方法：
public void start() throws Exception {
this.remotingServer.start();
if (this.fileWatchService != null) {
this.fileWatchService.start();
}
}
主要做了下面几件事情：
1）、在NamesrvController#initialize中：KVConfigManager配置加载
2）、在NamesrvController#initialize中：NettyRemotingServer实例的创建
3）、在NamesrvController#initialize中：创建定时线程任务每隔十秒扫描一次Broker，移除处于不 激活状态的Broker
4）、 定时线程每隔十分钟打印一次KV配置#initialize中：创建定时线程每隔十分钟打印一次KV配置
5）、注册了一个JVM钩子函数
6）、在NamesrvController#start中：NettyRemotingServer服务启动
7）、在NamesrvController#start中：FileWatchService线程如果不为空则启动他
3、至此就完成了NamesrvServer的启动（详细后面再看），简单流程图如下：