第二篇 hbase2.4.2 源码分析 RegionServer启动流程

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前言

1.看什么？ 看HRegionServer类说明 看main()入口 看初始化了哪些重要组件 如何进行远程调用 如何看：看过程中画图，或者把方法的调用关系，对象的调用按照调用关系记录下来，本文按照第二种方式进行编写

一、HRegionServer类继承关系

看什么？
看类说明，看继承关系
从哲学角度看：这是性质问题
HRegionServer 是个线程，实现 RegionServerServices, LastSequenceId, ConfigurationObserver 几个接口，既然是线程，肯定有run方法

/*** HRegionServer makes a set of HRegions available to clients. It checks in with* the HMaster. There are many HRegionServers in a single HBase deployment.*/
@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.TOOLS)
@SuppressWarnings({ "deprecation"})
public class HRegionServer extends Thread implementsRegionServerServices, LastSequenceId, ConfigurationObserver {

二、HRegionServer.main入口分析

1.main入口

  /*** @see org.apache.hadoop.hbase.regionserver.HRegionServerCommandLine*/public static void main(String[] args) {LOG.info("STARTING executorService " + HRegionServer.class.getSimpleName());VersionInfo.logVersion();Configuration conf = HBaseConfiguration.create();@SuppressWarnings("unchecked")Class<? extends HRegionServer> regionServerClass = (Class<? extends HRegionServer>) conf.getClass(HConstants.REGION_SERVER_IMPL, HRegionServer.class);new HRegionServerCommandLine(regionServerClass).doMain(args);}
HRegionServerCommandLine.doMain()如下/*** Parse and run the given command line. This may exit the JVM if* a nonzero exit code is returned from <code>run()</code>.*/public void doMain(String args[]) {try {//核心代码，为什么是核心代码？除了它，还有其他值得看的吗？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);}}public static int run(Configuration conf, Tool tool, String[] args) throws Exception {if (CallerContext.getCurrent() == null) {CallerContext ctx = (new Builder("CLI")).build();CallerContext.setCurrent(ctx);}if (conf == null) {conf = new Configuration();}GenericOptionsParser parser = new GenericOptionsParser(conf, args);tool.setConf(conf);String[] toolArgs = parser.getRemainingArgs();//在这里真正调用,org.apache.hadoop.util.Tool竟然是Hadoop包的，我在想，为什么，不直接在hbase包下启动就好了，吐槽。。。return tool.run(toolArgs);}tool就是：  HRegionServerCommandLine， 找HRegionServerCommandLine.run()@Overridepublic int run(String args[]) throws Exception {if (args.length != 1) {usage(null);return 1;}String cmd = args[0];if ("start".equals(cmd)) {//启动代码，追进去看看return start();} else if ("stop".equals(cmd)) {System.err.println("To shutdown the regionserver run " +"hbase-daemon.sh stop regionserver or send a kill signal to " +"the regionserver pid");return 1;} else {usage("Unknown command: " + args[0]);return 1;}}//到达启动流程
private int start() throws Exception {Configuration conf = getConf();TraceUtil.initTracer(conf);try {// If 'local', don't start a region server here. Defer to// LocalHBaseCluster. It manages 'local' clusters.//local模式if (LocalHBaseCluster.isLocal(conf)) {LOG.warn("Not starting a distinct region server because "+ HConstants.CLUSTER_DISTRIBUTED + " is false");} else {//集群模式logProcessInfo(getConf());HRegionServer hrs = HRegionServer.constructRegionServer(regionServerClass, conf);hrs.start(); //启动，触发HRegionServer的run方法hrs.join();  //等待线程结束if (hrs.isAborted()) {throw new RuntimeException("HRegionServer Aborted");}}} catch (Throwable t) {LOG.error("Region server exiting", t);return 1;}return 0;}

2.HRegionServer.run()分析 核心服务都在这启动

代码如下（示例）：

run()preRegistrationInitializationsetupClusterConnection()初始化clusterConnection和MetaTableLocatorinitializeZooKeeper()initializeThreads()跟master进行注册RegionServerStartupResponse w = reportForDuty();handleReportForDutyResponse()处理master返回的响应createMyEphemeralNode() 在zk的/rs目录进行注册（创建临时节点）initializeFileSystem();setupWALAndReplication();startReplicationService()JvmPauseMonitor() jvm fullGC停顿检测线程startServices() --启动很多服务和线程HeapMemoryManager管理器启动

三、 HRegionServer和master的rpc如何调用？

RegionServerStartupResponse w = reportForDuty();RegionServerStartupRequest.Builder request = RegionServerStartupRequest.newBuilder();if (!StringUtils.isBlank(useThisHostnameInstead)) {request.setUseThisHostnameInstead(useThisHostnameInstead);}request.setPort(port);request.setServerStartCode(this.startcode);request.setServerCurrentTime(now);这里的rss就是跟master交互的接口result = rss.regionServerStartup(null, request.build());

这种request.newBuilder().build() builder模式生成请求，然后进行rpc交互，采用google,gRpc协议通信
那怎么知道，哪个类接收到regionserver发起的rpc请求？     直接搜索regionServerStartup方法，看看有哪个类实现了该方法

发现是MasterRpcServices实现了，查看方法实现，只是把regionserver的信息放到一个map里面保存

调用栈：regionServerStartup checkAndRecordNewServerrecordNewServerWithLock/*** Adds the onlineServers list. onlineServers should be locked.* @param serverName The remote servers name.*/void recordNewServerWithLock(final ServerName serverName, final ServerMetrics sl) {LOG.info("Registering regionserver=" + serverName);this.onlineServers.put(serverName, sl);this.rsAdmins.remove(serverName);}

总结

regionserver启动 ： 构造器初始化，线程启动,run()方法调用，启动一堆看不懂服务。。。 rpc调用： 使用 gRpc框架

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