从main（）函数开始

  public static void main(String [] args) {
    VersionInfo.logVersion();
    new HMasterCommandLine(HMaster.class).doMain(args);
  }
    public void doMain(String args[]) {
    try {
      int ret = ToolRunner.run(HBaseConfiguration.create(), this, args);
      if (ret != 0) {
        System.exit(ret);
      }
    } catch (Exception e) {
      LOG.error("Failed to run", e);
      System.exit(-1);
    }
  }

这里是使用的hadoop的ToolRunner，

public static int More ...run(Configuration conf, Tool tool, String[] args) 
    throws Exception{
    if(conf == null) {
      conf = new Configuration();
    }
    GenericOptionsParser parser = new GenericOptionsParser(conf, args);
    //set the configuration back, so that Tool can configure itself
    tool.setConf(conf);

    //get the args w/o generic hadoop args
    String[] toolArgs = parser.getRemainingArgs();
    return tool.run(toolArgs);
  }

其实就是走了一遍GenericOptionsParser解析参数，又回到tool.run(toolArgs);而这里的tool其实有这样的继承关系HMasterCommandLine-->ServerCommandLine-->Tool,而这里的tool其实有这样的继承关系HMasterCommandLine的run（）方法

  public int run(String args[]) throws Exception {
    Options opt = new Options();
    opt.addOption("localRegionServers", true,
      "RegionServers to start in master process when running standalone");
    opt.addOption("masters", true, "Masters to start in this process");
    opt.addOption("minRegionServers", true, "Minimum RegionServers needed to host user tables");
    opt.addOption("backup", false, "Do not try to become HMaster until the primary fails");

    CommandLine cmd;
    try {
      cmd = new GnuParser().parse(opt, args);
    } catch (ParseException e) {
      LOG.error("Could not parse: ", e);
      usage(null);
      return 1;
    }


    if (cmd.hasOption("minRegionServers")) {
      String val = cmd.getOptionValue("minRegionServers");
      getConf().setInt("hbase.regions.server.count.min",
                  Integer.valueOf(val));
      LOG.debug("minRegionServers set to " + val);
    }

    // minRegionServers used to be minServers.  Support it too.
    if (cmd.hasOption("minServers")) {
      String val = cmd.getOptionValue("minServers");
      getConf().setInt("hbase.regions.server.count.min",
                  Integer.valueOf(val));
      LOG.debug("minServers set to " + val);
    }

    // check if we are the backup master - override the conf if so
    if (cmd.hasOption("backup")) {
      getConf().setBoolean(HConstants.MASTER_TYPE_BACKUP, true);
    }

    // How many regionservers to startup in this process (we run regionservers in same process as
    // master when we are in local/standalone mode. Useful testing)
    if (cmd.hasOption("localRegionServers")) {
      String val = cmd.getOptionValue("localRegionServers");
      getConf().setInt("hbase.regionservers", Integer.valueOf(val));
      LOG.debug("localRegionServers set to " + val);
    }
    // How many masters to startup inside this process; useful testing
    if (cmd.hasOption("masters")) {
      String val = cmd.getOptionValue("masters");
      getConf().setInt("hbase.masters", Integer.valueOf(val));
      LOG.debug("masters set to " + val);
    }

    List<String> remainingArgs = cmd.getArgList();
    if (remainingArgs.size() != 1) {
      usage(null);
      return 1;
    }

    String command = remainingArgs.get(0);

    if ("start".equals(command)) {
      return startMaster();
    } else if ("stop".equals(command)) {
      return stopMaster();
    } else if ("clear".equals(command)) {
      return (ZNodeClearer.clear(getConf()) ? 0 : 1);
    } else {
      usage("Invalid command: " + command);
      return 1;
    }
  }

启动的时候command="start",走startMaster（）

private int startMaster() {
    Configuration conf = getConf();
    try {
      // If ‘local‘, defer to LocalHBaseCluster instance.  Starts master
      // and regionserver both in the one JVM.
      if (LocalHBaseCluster.isLocal(conf)) {
        final MiniZooKeeperCluster zooKeeperCluster = new MiniZooKeeperCluster(conf);
        File zkDataPath = new File(conf.get(HConstants.ZOOKEEPER_DATA_DIR));
        int zkClientPort = conf.getInt(HConstants.ZOOKEEPER_CLIENT_PORT, 0);
        if (zkClientPort == 0) {
          throw new IOException("No config value for "
              + HConstants.ZOOKEEPER_CLIENT_PORT);
        }
        zooKeeperCluster.setDefaultClientPort(zkClientPort);

        // login the zookeeper server principal (if using security)
        ZKUtil.loginServer(conf, "hbase.zookeeper.server.keytab.file",
          "hbase.zookeeper.server.kerberos.principal", null);

        int clientPort = zooKeeperCluster.startup(zkDataPath);
        if (clientPort != zkClientPort) {
          String errorMsg = "Could not start ZK at requested port of " +
            zkClientPort + ".  ZK was started at port: " + clientPort +
            ".  Aborting as clients (e.g. shell) will not be able to find " +
            "this ZK quorum.";
          System.err.println(errorMsg);
          throw new IOException(errorMsg);
        }
        conf.set(HConstants.ZOOKEEPER_CLIENT_PORT,
                 Integer.toString(clientPort));
        // Need to have the zk cluster shutdown when master is shutdown.
        // Run a subclass that does the zk cluster shutdown on its way out.
        LocalHBaseCluster cluster = new LocalHBaseCluster(conf, conf.getInt("hbase.masters", 1),
          conf.getInt("hbase.regionservers", 1), LocalHMaster.class, HRegionServer.class);
        ((LocalHMaster)cluster.getMaster(0)).setZKCluster(zooKeeperCluster);
        cluster.startup();
        waitOnMasterThreads(cluster);
      } else {
        logProcessInfo(getConf());
        HMaster master = HMaster.constructMaster(masterClass, conf);
        if (master.isStopped()) {
          LOG.info("Won‘t bring the Master up as a shutdown is requested");
          return 1;
        }
        master.start();
        master.join();
        if(master.isAborted())
          throw new RuntimeException("HMaster Aborted");
      }
    } catch (Throwable t) {
      LOG.error("Master exiting", t);
      return 1;
    }
    return 0;
  }

如果LocalHBaseCluster.isLocal（），启动一个本地集群LocalHBaseCluster，这里会在同一个JVM启动HMaster,HRegionServer
这里默认：hbase.cluster.distributed=false

  /** Cluster is in distributed mode or not */
  public static final String CLUSTER_DISTRIBUTED = "hbase.cluster.distributed";

  /** Config for pluggable load balancers */
  public static final String HBASE_MASTER_LOADBALANCER_CLASS = "hbase.master.loadbalancer.class";

  /** Cluster is standalone or pseudo-distributed */
  public static final boolean CLUSTER_IS_LOCAL = false;
  public static boolean isLocal(final Configuration c) {
    boolean mode = c.getBoolean(HConstants.CLUSTER_DISTRIBUTED, HConstants.DEFAULT_CLUSTER_DISTRIBUTED);
    return(mode == HConstants.CLUSTER_IS_LOCAL);
  }

如果hbase.cluster.distributed=true,创建一个HMaster实例

logProcessInfo(getConf());
HMaster master = HMaster.constructMaster(masterClass, conf);
if (master.isStopped()) {
  LOG.info("Won‘t bring the Master up as a shutdown is requested");
  return 1;
}
master.start();
master.join();
if(master.isAborted())
  throw new RuntimeException("HMaster Aborted");

构造HMaster

 Constructor<? extends HMaster> c =
        masterClass.getConstructor(Configuration.class);
      return c.newInstance(conf);

正是的构造函数：
1，获取master的地址，ip:port

public static final String MASTER_PORT = "hbase.master.port";为端口，默认60000
int port = conf.getInt(HConstants.MASTER_PORT, HConstants.DEFAULT_MASTER_PORT);

2，处理RPC的handler的数量，由hbase.regionserver.handler.count
3，创建HMaster的RPCServer实例.
4，启动RPCServer的线程,
5, 创建zookeeper，创建hbase相关节点

  public HMaster(final Configuration conf)
  throws IOException, KeeperException, InterruptedException {
    this.conf = new Configuration(conf);
    // Disable the block cache on the master
    this.conf.setFloat(HConstants.HFILE_BLOCK_CACHE_SIZE_KEY, 0.0f);
    // Server to handle client requests.
    String hostname = Strings.domainNamePointerToHostName(DNS.getDefaultHost(
      conf.get("hbase.master.dns.interface", "default"),
      conf.get("hbase.master.dns.nameserver", "default")));
    int port = conf.getInt(HConstants.MASTER_PORT, HConstants.DEFAULT_MASTER_PORT);
    // Test that the hostname is reachable
    InetSocketAddress initialIsa = new InetSocketAddress(hostname, port);
    if (initialIsa.getAddress() == null) {
      throw new IllegalArgumentException("Failed resolve of hostname " + initialIsa);
    }
    // Verify that the bind address is reachable if set
    String bindAddress = conf.get("hbase.master.ipc.address");
    if (bindAddress != null) {
      initialIsa = new InetSocketAddress(bindAddress, port);
      if (initialIsa.getAddress() == null) {
        throw new IllegalArgumentException("Failed resolve of bind address " + initialIsa);
      }
    }
    String name = "master/" + initialIsa.toString();
    // Set how many times to retry talking to another server over HConnection.
    HConnectionManager.setServerSideHConnectionRetries(this.conf, name, LOG);
    int numHandlers = conf.getInt("hbase.master.handler.count",
      conf.getInt("hbase.regionserver.handler.count", 25));
    this.rpcServer = new RpcServer(this, name, getServices(),
      initialIsa, // BindAddress is IP we got for this server.
      numHandlers,
      0, // we dont use high priority handlers in master
      conf,
      0); // this is a DNC w/o high priority handlers
    // Set our address.
    this.isa = this.rpcServer.getListenerAddress();
    // We don‘t want to pass isa‘s hostname here since it could be 0.0.0.0
    this.serverName = new ServerName(hostname, this.isa.getPort(), System.currentTimeMillis());
    this.rsFatals = new MemoryBoundedLogMessageBuffer(
      conf.getLong("hbase.master.buffer.for.rs.fatals", 1*1024*1024));

    // login the zookeeper client principal (if using security)
    ZKUtil.loginClient(this.conf, "hbase.zookeeper.client.keytab.file",
      "hbase.zookeeper.client.kerberos.principal", this.isa.getHostName());

    // initialize server principal (if using secure Hadoop)
    User.login(conf, "hbase.master.keytab.file",
      "hbase.master.kerberos.principal", this.isa.getHostName());

    LOG.info("hbase.rootdir=" + FSUtils.getRootDir(this.conf) +
        ", hbase.cluster.distributed=" + this.conf.getBoolean("hbase.cluster.distributed", false));

    // set the thread name now we have an address
    setName(MASTER + ":" + this.serverName.toShortString());

    Replication.decorateMasterConfiguration(this.conf);

    // Hack! Maps DFSClient => Master for logs.  HDFS made this
    // config param for task trackers, but we can piggyback off of it.
    if (this.conf.get("mapred.task.id") == null) {
      this.conf.set("mapred.task.id", "hb_m_" + this.serverName.toString());
    }

    this.zooKeeper = new ZooKeeperWatcher(conf, MASTER + ":" + isa.getPort(), this, true);
    this.rpcServer.startThreads();
    this.pauseMonitor = new JvmPauseMonitor(conf);
    this.pauseMonitor.start();

    // metrics interval: using the same property as region server.
    this.msgInterval = conf.getInt("hbase.regionserver.msginterval", 3 * 1000);

    //should we check the compression codec type at master side, default true, HBASE-6370
    this.masterCheckCompression = conf.getBoolean("hbase.master.check.compression", true);

    this.metricsMaster = new MetricsMaster( new MetricsMasterWrapperImpl(this));

    // Health checker thread.
    int sleepTime = this.conf.getInt(HConstants.HEALTH_CHORE_WAKE_FREQ,
      HConstants.DEFAULT_THREAD_WAKE_FREQUENCY);
    if (isHealthCheckerConfigured()) {
      healthCheckChore = new HealthCheckChore(sleepTime, this, getConfiguration());
    }

    // Do we publish the status?
    boolean shouldPublish = conf.getBoolean(HConstants.STATUS_PUBLISHED,
        HConstants.STATUS_PUBLISHED_DEFAULT);
    Class<? extends ClusterStatusPublisher.Publisher> publisherClass =
        conf.getClass(ClusterStatusPublisher.STATUS_PUBLISHER_CLASS,
            ClusterStatusPublisher.DEFAULT_STATUS_PUBLISHER_CLASS,
            ClusterStatusPublisher.Publisher.class);

    if (shouldPublish) {
      if (publisherClass == null) {
        LOG.warn(HConstants.STATUS_PUBLISHED + " is true, but " +
            ClusterStatusPublisher.DEFAULT_STATUS_PUBLISHER_CLASS +
            " is not set - not publishing status");
      } else {
        clusterStatusPublisherChore = new ClusterStatusPublisher(this, conf, publisherClass);
        Threads.setDaemonThreadRunning(clusterStatusPublisherChore.getThread());
      }
    }

    distributedLogReplay = this.conf.getBoolean(HConstants.DISTRIBUTED_LOG_REPLAY_KEY,
      HConstants.DEFAULT_DISTRIBUTED_LOG_REPLAY_CONFIG);
  }

创建zookeeper，连接到zookeeper,创建hbase相关节点。
这里主要两个函数setNodeNames（）和createBaseZNodes（）

this.zooKeeper = new ZooKeeperWatcher(conf, MASTER + ":" + isa.getPort(), this, true);

  public ZooKeeperWatcher(Configuration conf, String identifier,
      Abortable abortable, boolean canCreateBaseZNode)
  throws IOException, ZooKeeperConnectionException {
    this.conf = conf;
    // Capture a stack trace now.  Will print it out later if problem so we can
    // distingush amongst the myriad ZKWs.
    try {
      throw new Exception("ZKW CONSTRUCTOR STACK TRACE FOR DEBUGGING");
    } catch (Exception e) {
      this.constructorCaller = e;
    }
    this.quorum = ZKConfig.getZKQuorumServersString(conf);
    // Identifier will get the sessionid appended later below down when we
    // handle the syncconnect event.
    this.identifier = identifier;
    this.abortable = abortable;
    setNodeNames(conf);
    this.recoverableZooKeeper = ZKUtil.connect(conf, quorum, this, identifier);
    if (canCreateBaseZNode) {
      createBaseZNodes();
    }
  }

HMaster的主循环的run（）方法，这里主要关心
1，becomeActiveMaster(startupStatus);

2，finishInitialization(startupStatus, false);

3，loop()

  @Override
  public void run() {
    MonitoredTask startupStatus =
      TaskMonitor.get().createStatus("Master startup");
    startupStatus.setDescription("Master startup");
    masterStartTime = System.currentTimeMillis();
    try {
      this.registeredZKListenersBeforeRecovery = this.zooKeeper.getListeners();
      this.masterAddressManager = new MasterAddressTracker(getZooKeeperWatcher(), this);
      this.masterAddressManager.start();

      // Put up info server.
      int port = this.conf.getInt("hbase.master.info.port", 60010);
      if (port >= 0) {
        String a = this.conf.get("hbase.master.info.bindAddress", "0.0.0.0");
        this.infoServer = new InfoServer(MASTER, a, port, false, this.conf);
        this.infoServer.addServlet("status", "/master-status", MasterStatusServlet.class);
        this.infoServer.addServlet("dump", "/dump", MasterDumpServlet.class);
        this.infoServer.setAttribute(MASTER, this);
        this.infoServer.start();
      }

      /*
       * Block on becoming the active master.
       *
       * We race with other masters to write our address into ZooKeeper.  If we
       * succeed, we are the primary/active master and finish initialization.
       *
       * If we do not succeed, there is another active master and we should
       * now wait until it dies to try and become the next active master.  If we
       * do not succeed on our first attempt, this is no longer a cluster startup.
       */
      becomeActiveMaster(startupStatus);

      // We are either the active master or we were asked to shutdown
      if (!this.stopped) {
        finishInitialization(startupStatus, false);
        loop();
      }
    } catch (Throwable t) {
      // HBASE-5680: Likely hadoop23 vs hadoop 20.x/1.x incompatibility
      if (t instanceof NoClassDefFoundError &&
          t.getMessage().contains("org/apache/hadoop/hdfs/protocol/FSConstants$SafeModeAction")) {
          // improved error message for this special case
          abort("HBase is having a problem with its Hadoop jars.  You may need to "
              + "recompile HBase against Hadoop version "
              +  org.apache.hadoop.util.VersionInfo.getVersion()
              + " or change your hadoop jars to start properly", t);
      } else {
        abort("Unhandled exception. Starting shutdown.", t);
      }
    } finally {
      startupStatus.cleanup();

      stopChores();
      // Wait for all the remaining region servers to report in IFF we were
      // running a cluster shutdown AND we were NOT aborting.
      if (!this.abort && this.serverManager != null &&
          this.serverManager.isClusterShutdown()) {
        this.serverManager.letRegionServersShutdown();
      }
      stopServiceThreads();
      // Stop services started for both backup and active masters
      if (this.activeMasterManager != null) this.activeMasterManager.stop();
      if (this.catalogTracker != null) this.catalogTracker.stop();
      if (this.serverManager != null) this.serverManager.stop();
      if (this.assignmentManager != null) this.assignmentManager.stop();
      if (this.fileSystemManager != null) this.fileSystemManager.stop();
      if (this.snapshotManager != null) this.snapshotManager.stop("server shutting down.");
      this.zooKeeper.close();
    }
    LOG.info("HMaster main thread exiting");
  }