（三）elasticsearch 源码之启动流程分析
https://www.cnblogs.com/darcy-yuan/p/17007635.html
1.前面我们在《（一）elasticsearch 编译和启动》和 《（二）elasticsearch 源码目录 》简单了解下es（elasticsearch，下同），现在我们来看下启动代码
下面是启动流程图，我们按照流程图的顺序依次描述
2.启动流程
org.elasticsearch.bootstrap.Elasticsearch
public static void main(final String[] args) throws Exception {
overrideDnsCachePolicyProperties();
/*
* We want the JVM to think there is a security manager installed so that if internal policy decisions that would be based on the
* presence of a security manager or lack thereof act as if there is a security manager present (e.g., DNS cache policy). This
* forces such policies to take effect immediately.
*/
System.setSecurityManager(new SecurityManager() {
@Override
public void checkPermission(Permission perm) {
// grant all permissions so that we can later set the security manager to the one that we want
}
});
LogConfigurator.registerErrorListener();
final Elasticsearch elasticsearch = new Elasticsearch();
int status = main(args, elasticsearch, Terminal.DEFAULT);
if (status != ExitCodes.OK) {
exit(status);
}
}后续执行 Elasticsearch.execute -> Elasticsearch.init -> Bootstrap.init
org.elasticsearch.bootstrap.Bootstrap
static void init(
final boolean foreground,
final Path pidFile,
final boolean quiet,
final Environment initialEnv) throws BootstrapException, NodeValidationException, UserException {
// force the class initializer for BootstrapInfo to run before
// the security manager is installed
BootstrapInfo.init();
INSTANCE = new Bootstrap();
// 安全配置文件
final SecureSettings keystore = loadSecureSettings(initialEnv);
final Environment environment = createEnvironment(pidFile, keystore, initialEnv.settings(), initialEnv.configFile());
LogConfigurator.setNodeName(Node.NODE_NAME_SETTING.get(environment.settings()));
try {
LogConfigurator.configure(environment);
} catch (IOException e) {
throw new BootstrapException(e);
}
if (JavaVersion.current().compareTo(JavaVersion.parse("11")) < 0) {
final String message = String.format(
Locale.ROOT,
"future versions of Elasticsearch will require Java 11; " +
"your Java version from [%s] does not meet this requirement",
System.getProperty("java.home"));
new DeprecationLogger(LogManager.getLogger(Bootstrap.class)).deprecated(message);
}
// 处理pidFile
if (environment.pidFile() != null) {
try {
PidFile.create(environment.pidFile(), true);
} catch (IOException e) {
throw new BootstrapException(e);
}
}
// 如果是后台启动，则不打印日志
final boolean closeStandardStreams = (foreground == false) || quiet;
try {
if (closeStandardStreams) {
final Logger rootLogger = LogManager.getRootLogger();
final Appender maybeConsoleAppender = Loggers.findAppender(rootLogger, ConsoleAppender.class);
if (maybeConsoleAppender != null) {
Loggers.removeAppender(rootLogger, maybeConsoleAppender);
}
closeSystOut();
}
// fail if somebody replaced the lucene jars
checkLucene();
// 通用异常捕获
// install the default uncaught exception handler; must be done before security is
// initialized as we do not want to grant the runtime permission
// setDefaultUncaughtExceptionHandler
Thread.setDefaultUncaughtExceptionHandler(new ElasticsearchUncaughtExceptionHandler());
INSTANCE.setup(true, environment);
try {
// any secure settings must be read during node construction
IOUtils.close(keystore);
} catch (IOException e) {
throw new BootstrapException(e);
}
INSTANCE.start();
if (closeStandardStreams) {
closeSysError();
}
}这里我们可以关注下 INSTANCE.setup(true, environment);
org.elasticsearch.bootstrap.Bootstrap
private void setup(boolean addShutdownHook, Environment environment) throws BootstrapException {
Settings settings = environment.settings();
try {
spawner.spawnNativeControllers(environment);
} catch (IOException e) {
throw new BootstrapException(e);
}
// 检查一些mlock设定
initializeNatives(
environment.tmpFile(),
BootstrapSettings.MEMORY_LOCK_SETTING.get(settings),
BootstrapSettings.SYSTEM_CALL_FILTER_SETTING.get(settings),
BootstrapSettings.CTRLHANDLER_SETTING.get(settings));
// 探针
// initialize probes before the security manager is installed
initializeProbes();
if (addShutdownHook) {
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
try {
IOUtils.close(node, spawner);
LoggerContext context = (LoggerContext) LogManager.getContext(false);
Configurator.shutdown(context);
if (node != null && node.awaitClose(10, TimeUnit.SECONDS) == false) {
throw new IllegalStateException("Node didn't stop within 10 seconds. " +
"Any outstanding requests or tasks might get killed.");
}
} catch (IOException ex) {
throw new ElasticsearchException("failed to stop node", ex);
} catch (InterruptedException e) {
LogManager.getLogger(Bootstrap.class).warn("Thread got interrupted while waiting for the node to shutdown.");
Thread.currentThread().interrupt();
}
}
});
}
try {
// 检查类加载的一些问题
// look for jar hell
final Logger logger = LogManager.getLogger(JarHell.class);
JarHell.checkJarHell(logger::debug);
} catch (IOException | URISyntaxException e) {
throw new BootstrapException(e);
}
// Log ifconfig output before SecurityManager is installed
IfConfig.logIfNecessary();
// 安全处理
// install SM after natives, shutdown hooks, etc.
try {
Security.configure(environment, BootstrapSettings.SECURITY_FILTER_BAD_DEFAULTS_SETTING.get(settings));
} catch (IOException | NoSuchAlgorithmException e) {
throw new BootstrapException(e);
}
node = new Node(environment) {
@Override
protected void validateNodeBeforeAcceptingRequests(
final BootstrapContext context,
final BoundTransportAddress boundTransportAddress, List checks) throws NodeValidationException {
BootstrapChecks.check(context, boundTransportAddress, checks);
}
};
} 最后一句 node = new Node(environment) 初始化了节点，里面做了许多工作
org.elasticsearch.node.Node
protected Node(
final Environment environment, Collection> classpathPlugins, boolean forbidPrivateIndexSettings) {
...
// 打印jvm信息
final JvmInfo jvmInfo = JvmInfo.jvmInfo();
logger.info(
"version[{}], pid[{}], build[{}/{}/{}/{}], OS[{}/{}/{}], JVM[{}/{}/{}/{}]",
Build.CURRENT.getQualifiedVersion(),
jvmInfo.pid(),
Build.CURRENT.flavor().displayName(),
Build.CURRENT.type().displayName(),
Build.CURRENT.hash(),
Build.CURRENT.date(),
Constants.OS_NAME,
Constants.OS_VERSION,
Constants.OS_ARCH,
Constants.JVM_VENDOR,
Constants.JVM_NAME,
Constants.JAVA_VERSION,
Constants.JVM_VERSION);
...
// 初始化各类服务，以及他们相关的依赖
this.pluginsService = new PluginsService(tmpSettings, environment.configFile(), environment.modulesFile(),
environment.pluginsFile(), classpathPlugins);
final Settings settings = pluginsService.updatedSettings();
final Set possibleRoles = Stream.concat(
DiscoveryNodeRole.BUILT_IN_ROLES.stream(),
pluginsService.filterPlugins(Plugin.class)
.stream()
.map(Plugin::getRoles)
.flatMap(Set::stream))
.collect(Collectors.toSet());
DiscoveryNode.setPossibleRoles(possibleRoles);
localNodeFactory = new LocalNodeFactory(settings, nodeEnvironment.nodeId());
...
// guice注入
modules.add(b -> {
b.bind(Node.class).toInstance(this);
b.bind(NodeService.class).toInstance(nodeService);
b.bind(NamedXContentRegistry.class).toInstance(xContentRegistry);
b.bind(PluginsService.class).toInstance(pluginsService);
b.bind(Client.class).toInstance(client);
b.bind(NodeClient.class).toInstance(client);
b.bind(Environment.class).toInstance(this.environment);
b.bind(ThreadPool.class).toInstance(threadPool); es 使用 guice注入框架，guice是个非常轻量级的依赖注入框架，既然各个组件都已经注入好了，我们现在可以启动了。
INSTANCE.start -> Bootstrap.start
org.elasticsearch.bootstrap.Bootstrap
private void start() throws NodeValidationException {
node.start();
keepAliveThread.start();
}node.start中启动各个组件。es中的各个组件继承了 AbstractLifecycleComponent。start方法会调用组件的doStart方法。
org.elasticsearch.node.Node
public Node start() throws NodeValidationException {
if (!lifecycle.moveToStarted()) {
return this;
}
logger.info("starting ...");
pluginLifecycleComponents.forEach(LifecycleComponent::start);
injector.getInstance(MappingUpdatedAction.class).setClient(client);
injector.getInstance(IndicesService.class).start();
injector.getInstance(IndicesClusterStateService.class).start();
injector.getInstance(SnapshotsService.class).start();
injector.getInstance(SnapshotShardsService.class).start();
injector.getInstance(SearchService.class).start();
nodeService.getMonitorService().start();
final ClusterService clusterService = injector.getInstance(ClusterService.class);
final NodeConnectionsService nodeConnectionsService = injector.getInstance(NodeConnectionsService.class);
nodeConnectionsService.start();
clusterService.setNodeConnectionsService(nodeConnectionsService);
...具体的我们看两个比较重要的服务 transportService.start();
org.elasticsearch.transport.TransportService
@Override
protected void doStart() {
transport.setMessageListener(this);
connectionManager.addListener(this);
// 建立网络连接
transport.start();
if (transport.boundAddress() != null && logger.isInfoEnabled()) {
logger.info("{}", transport.boundAddress());
for (Map.Entry entry : transport.profileBoundAddresses().entrySet()) {
logger.info("profile [{}]: {}", entry.getKey(), entry.getValue());
}
}
localNode = localNodeFactory.apply(transport.boundAddress());
if (connectToRemoteCluster) {
// here we start to connect to the remote clusters
remoteClusterService.initializeRemoteClusters();
}
} 启动transport的实现类是 SecurityNetty4HttpServerTransport
另一个比较重要的服务，discovery.start()，具体实现类是 Coordinator
org.elasticsearch.cluster.coordination.Coordinator
@Override
protected void doStart() {
synchronized (mutex) {
CoordinationState.PersistedState persistedState = persistedStateSupplier.get();
coordinationState.set(new CoordinationState(getLocalNode(), persistedState, electionStrategy));
peerFinder.setCurrentTerm(getCurrentTerm());
configuredHostsResolver.start();
final ClusterState lastAcceptedState = coordinationState.get().getLastAcceptedState();
if (lastAcceptedState.metaData().clusterUUIDCommitted()) {
logger.info("cluster UUID [{}]", lastAcceptedState.metaData().clusterUUID());
}
final VotingConfiguration votingConfiguration = lastAcceptedState.getLastCommittedConfiguration();
if (singleNodeDiscovery &&
votingConfiguration.isEmpty() == false &&
votingConfiguration.hasQuorum(Collections.singleton(getLocalNode().getId())) == false) {
throw new IllegalStateException("cannot start with [" + DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey() + "] set to [" +
DiscoveryModule.SINGLE_NODE_DISCOVERY_TYPE + "] when local node " + getLocalNode() +
" does not have quorum in voting configuration " + votingConfiguration);
}
...