聊聊arthas的ArthasBootstrap

序

本文主要研究一下arthas的ArthasBootstrap

getInstance

com/taobao/arthas/core/server/ArthasBootstrap.java

    /**
     * 单例
     *
     * @param instrumentation JVM增强
     * @return ArthasServer单例
     * @throws Throwable
     */
    public synchronized static ArthasBootstrap getInstance(Instrumentation instrumentation, Map<String, String> args) throws Throwable {
        if (arthasBootstrap == null) {
            arthasBootstrap = new ArthasBootstrap(instrumentation, args);
        }
        return arthasBootstrap;
    }

ArthasBootstrap提供了getInstance的静态方法用户创建ArthasBootstrap

ArthasBootstrap

public class ArthasBootstrap {
    private static final String ARTHAS_SPY_JAR = "arthas-spy.jar";
    public static final String ARTHAS_HOME_PROPERTY = "arthas.home";
    private static String ARTHAS_HOME = null;

    public static final String CONFIG_NAME_PROPERTY = "arthas.config.name";
    public static final String CONFIG_LOCATION_PROPERTY = "arthas.config.location";
    public static final String CONFIG_OVERRIDE_ALL = "arthas.config.overrideAll";

    private static ArthasBootstrap arthasBootstrap;

    private ArthasEnvironment arthasEnvironment;
    private Configure configure;

    private AtomicBoolean isBindRef = new AtomicBoolean(false);
    private Instrumentation instrumentation;
    private InstrumentTransformer classLoaderInstrumentTransformer;
    private Thread shutdown;
    private ShellServer shellServer;
    private ScheduledExecutorService executorService;
    private SessionManager sessionManager;
    private TunnelClient tunnelClient;

    private File outputPath;

    private static LoggerContext loggerContext;
    private EventExecutorGroup workerGroup;

    private Timer timer = new Timer("arthas-timer", true);

    private TransformerManager transformerManager;

    private ResultViewResolver resultViewResolver;

    private HistoryManager historyManager;

    private HttpApiHandler httpApiHandler;

    private HttpSessionManager httpSessionManager;
    private SecurityAuthenticator securityAuthenticator;

    private ArthasBootstrap(Instrumentation instrumentation, Map<String, String> args) throws Throwable {
        this.instrumentation = instrumentation;

        initFastjson();

        // 1. initSpy()
        initSpy();
        // 2. ArthasEnvironment
        initArthasEnvironment(args);

        String outputPathStr = configure.getOutputPath();
        if (outputPathStr == null) {
            outputPathStr = ArthasConstants.ARTHAS_OUTPUT;
        }
        outputPath = new File(outputPathStr);
        outputPath.mkdirs();

        // 3. init logger
        loggerContext = LogUtil.initLogger(arthasEnvironment);

        // 4. 增强ClassLoader
        enhanceClassLoader();
        // 5. init beans
        initBeans();

        // 6. start agent server
        bind(configure);

        executorService = Executors.newScheduledThreadPool(1, new ThreadFactory() {
            @Override
            public Thread newThread(Runnable r) {
                final Thread t = new Thread(r, "arthas-command-execute");
                t.setDaemon(true);
                return t;
            }
        });

        shutdown = new Thread("as-shutdown-hooker") {

            @Override
            public void run() {
                ArthasBootstrap.this.destroy();
            }
        };

        transformerManager = new TransformerManager(instrumentation);
        Runtime.getRuntime().addShutdownHook(shutdown);
    }

    //......
}    

ArthasBootstrap的构造器执行initFastjson、initSpy、initArthasEnvironment、LogUtil.initLogger(arthasEnvironment)、enhanceClassLoader、initBeans、bind，最后注册shutdownHook来执行destroy方法

initFastjson

    private void initFastjson() {
        // ignore getter error #1661
        // #2081
        JSON.config(JSONWriter.Feature.IgnoreErrorGetter, JSONWriter.Feature.WriteNonStringKeyAsString);
    }

initFastjson这里使用fastjson2的config方法来忽略getter的error，以及设置WriteNonStringKeyAsString

initSpy

    private void initSpy() throws Throwable {
        // TODO init SpyImpl ?

        // 将Spy添加到BootstrapClassLoader
        ClassLoader parent = ClassLoader.getSystemClassLoader().getParent();
        Class<?> spyClass = null;
        if (parent != null) {
            try {
                spyClass =parent.loadClass("java.arthas.SpyAPI");
            } catch (Throwable e) {
                // ignore
            }
        }
        if (spyClass == null) {
            CodeSource codeSource = ArthasBootstrap.class.getProtectionDomain().getCodeSource();
            if (codeSource != null) {
                File arthasCoreJarFile = new File(codeSource.getLocation().toURI().getSchemeSpecificPart());
                File spyJarFile = new File(arthasCoreJarFile.getParentFile(), ARTHAS_SPY_JAR);
                instrumentation.appendToBootstrapClassLoaderSearch(new JarFile(spyJarFile));
            } else {
                throw new IllegalStateException("can not find " + ARTHAS_SPY_JAR);
            }
        }
    }

initSpy将Spy添加到BootstrapClassLoader

initArthasEnvironment

    private void initArthasEnvironment(Map<String, String> argsMap) throws IOException {
        if (arthasEnvironment == null) {
            arthasEnvironment = new ArthasEnvironment();
        }

        /**
         * <pre>
         * 脚本里传过来的配置项，即命令行参数 > System Env > System Properties > arthas.properties
         * arthas.properties 提供一个配置项，可以反转优先级。 arthas.config.overrideAll=true
         * https://github.com/alibaba/arthas/issues/986
         * </pre>
         */
        Map<String, Object> copyMap;
        if (argsMap != null) {
            copyMap = new HashMap<String, Object>(argsMap);
            // 添加 arthas.home
            if (!copyMap.containsKey(ARTHAS_HOME_PROPERTY)) {
                copyMap.put(ARTHAS_HOME_PROPERTY, arthasHome());
            }
        } else {
            copyMap = new HashMap<String, Object>(1);
            copyMap.put(ARTHAS_HOME_PROPERTY, arthasHome());
        }

        MapPropertySource mapPropertySource = new MapPropertySource("args", copyMap);
        arthasEnvironment.addFirst(mapPropertySource);

        tryToLoadArthasProperties();

        configure = new Configure();
        BinderUtils.inject(arthasEnvironment, configure);
    }

initArthasEnvironment按命令行参数 > System Env > System Properties > arthas.properties这个顺序来配置ArthasEnvironment

initLogger

    public static LoggerContext initLogger(ArthasEnvironment env) {
        String loggingConfig = env.resolvePlaceholders(LOGGING_CONFIG);
        if (loggingConfig == null || loggingConfig.trim().isEmpty()) {
            return null;
        }
        AnsiLog.debug("arthas logging file: " + loggingConfig);
        File configFile = new File(loggingConfig);
        if (!configFile.isFile()) {
            AnsiLog.error("can not find arthas logging config: " + loggingConfig);
            return null;
        }

        try {
            LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
            loggerContext.reset();

            String fileName = env.getProperty(FILE_NAME_PROPERTY);
            if (fileName != null) {
                loggerContext.putProperty(ARTHAS_LOG_FILE, fileName);
            }
            String filePath = env.getProperty(FILE_PATH_PROPERTY);
            if (filePath != null) {
                loggerContext.putProperty(ARTHAS_LOG_PATH, filePath);
            }

            JoranConfigurator configurator = new JoranConfigurator();
            configurator.setContext(loggerContext);
            configurator.doConfigure(configFile.toURI().toURL()); // load logback xml file

            // 查找 arthas.log appender
            Iterator<Appender<ILoggingEvent>> appenders = loggerContext.getLogger("root").iteratorForAppenders();

            while (appenders.hasNext()) {
                Appender<ILoggingEvent> appender = appenders.next();
                if (appender instanceof RollingFileAppender) {
                    RollingFileAppender fileAppender = (RollingFileAppender) appender;
                    if ("ARTHAS".equalsIgnoreCase(fileAppender.getName())) {
                        logFile = new File(fileAppender.getFile()).getCanonicalPath();
                    }
                }
            }

            return loggerContext;
        } catch (Throwable e) {
            AnsiLog.error("try to load arthas logging config file error: " + configFile, e);
        }
        return null;
    }

initLogger从env获取相应的日志配置，然后设置到LoggerContext，然后设置到logback的JoranConfigurator

enhanceClassLoader

    void enhanceClassLoader() throws IOException, UnmodifiableClassException {
        if (configure.getEnhanceLoaders() == null) {
            return;
        }
        Set<String> loaders = new HashSet<String>();
        for (String s : configure.getEnhanceLoaders().split(",")) {
            loaders.add(s.trim());
        }

        // 增强 ClassLoader#loadClsss ，解决一些ClassLoader加载不到 SpyAPI的问题
        // https://github.com/alibaba/arthas/issues/1596
        byte[] classBytes = IOUtils.getBytes(ArthasBootstrap.class.getClassLoader()
                .getResourceAsStream(ClassLoader_Instrument.class.getName().replace('.', '/') + ".class"));

        SimpleClassMatcher matcher = new SimpleClassMatcher(loaders);
        InstrumentConfig instrumentConfig = new InstrumentConfig(AsmUtils.toClassNode(classBytes), matcher);

        InstrumentParseResult instrumentParseResult = new InstrumentParseResult();
        instrumentParseResult.addInstrumentConfig(instrumentConfig);
        classLoaderInstrumentTransformer = new InstrumentTransformer(instrumentParseResult);
        instrumentation.addTransformer(classLoaderInstrumentTransformer, true);

        if (loaders.size() == 1 && loaders.contains(ClassLoader.class.getName())) {
            // 如果只增强 java.lang.ClassLoader，可以减少查找过程
            instrumentation.retransformClasses(ClassLoader.class);
        } else {
            InstrumentationUtils.trigerRetransformClasses(instrumentation, loaders);
        }
    }

enhanceClassLoader会使用instrumentation来增强configure.getEnhanceLoaders()

initBeans

    private void initBeans() {
        this.resultViewResolver = new ResultViewResolver();
        this.historyManager = new HistoryManagerImpl();
    }

initBeans则创建ResultViewResolver、HistoryManagerImpl

bind

    private void bind(Configure configure) throws Throwable {

        long start = System.currentTimeMillis();

        if (!isBindRef.compareAndSet(false, true)) {
            throw new IllegalStateException("already bind");
        }

        // init random port
        if (configure.getTelnetPort() != null && configure.getTelnetPort() == 0) {
            int newTelnetPort = SocketUtils.findAvailableTcpPort();
            configure.setTelnetPort(newTelnetPort);
            logger().info("generate random telnet port: " + newTelnetPort);
        }
        if (configure.getHttpPort() != null && configure.getHttpPort() == 0) {
            int newHttpPort = SocketUtils.findAvailableTcpPort();
            configure.setHttpPort(newHttpPort);
            logger().info("generate random http port: " + newHttpPort);
        }
        // try to find appName
        if (configure.getAppName() == null) {
            configure.setAppName(System.getProperty(ArthasConstants.PROJECT_NAME,
                    System.getProperty(ArthasConstants.SPRING_APPLICATION_NAME, null)));
        }

        try {
            if (configure.getTunnelServer() != null) {
                tunnelClient = new TunnelClient();
                tunnelClient.setAppName(configure.getAppName());
                tunnelClient.setId(configure.getAgentId());
                tunnelClient.setTunnelServerUrl(configure.getTunnelServer());
                tunnelClient.setVersion(ArthasBanner.version());
                ChannelFuture channelFuture = tunnelClient.start();
                channelFuture.await(10, TimeUnit.SECONDS);
            }
        } catch (Throwable t) {
            logger().error("start tunnel client error", t);
        }

        try {
            ShellServerOptions options = new ShellServerOptions()
                            .setInstrumentation(instrumentation)
                            .setPid(PidUtils.currentLongPid())
                            .setWelcomeMessage(ArthasBanner.welcome());
            if (configure.getSessionTimeout() != null) {
                options.setSessionTimeout(configure.getSessionTimeout() * 1000);
            }

            this.httpSessionManager = new HttpSessionManager();
            if (IPUtils.isAllZeroIP(configure.getIp()) && StringUtils.isBlank(configure.getPassword())) {
                // 当 listen 0.0.0.0 时，强制生成密码，防止被远程连接
                String errorMsg = "Listening on 0.0.0.0 is very dangerous! External users can connect to your machine! "
                        + "No password is currently configured. " + "Therefore, a default password is generated, "
                        + "and clients need to use the password to connect!";
                AnsiLog.error(errorMsg);
                configure.setPassword(StringUtils.randomString(64));
                AnsiLog.error("Generated arthas password: " + configure.getPassword());

                logger().error(errorMsg);
                logger().info("Generated arthas password: " + configure.getPassword());
            }

            this.securityAuthenticator = new SecurityAuthenticatorImpl(configure.getUsername(), configure.getPassword());

            shellServer = new ShellServerImpl(options);

            List<String> disabledCommands = new ArrayList<String>();
            if (configure.getDisabledCommands() != null) {
                String[] strings = StringUtils.tokenizeToStringArray(configure.getDisabledCommands(), ",");
                if (strings != null) {
                    disabledCommands.addAll(Arrays.asList(strings));
                }
            }
            BuiltinCommandPack builtinCommands = new BuiltinCommandPack(disabledCommands);
            List<CommandResolver> resolvers = new ArrayList<CommandResolver>();
            resolvers.add(builtinCommands);

            //worker group
            workerGroup = new NioEventLoopGroup(new DefaultThreadFactory("arthas-TermServer", true));

            // TODO: discover user provided command resolver
            if (configure.getTelnetPort() != null && configure.getTelnetPort() > 0) {
                logger().info("try to bind telnet server, host: {}, port: {}.", configure.getIp(), configure.getTelnetPort());
                shellServer.registerTermServer(new HttpTelnetTermServer(configure.getIp(), configure.getTelnetPort(),
                        options.getConnectionTimeout(), workerGroup, httpSessionManager));
            } else {
                logger().info("telnet port is {}, skip bind telnet server.", configure.getTelnetPort());
            }
            if (configure.getHttpPort() != null && configure.getHttpPort() > 0) {
                logger().info("try to bind http server, host: {}, port: {}.", configure.getIp(), configure.getHttpPort());
                shellServer.registerTermServer(new HttpTermServer(configure.getIp(), configure.getHttpPort(),
                        options.getConnectionTimeout(), workerGroup, httpSessionManager));
            } else {
                // listen local address in VM communication
                if (configure.getTunnelServer() != null) {
                    shellServer.registerTermServer(new HttpTermServer(configure.getIp(), configure.getHttpPort(),
                            options.getConnectionTimeout(), workerGroup, httpSessionManager));
                }
                logger().info("http port is {}, skip bind http server.", configure.getHttpPort());
            }

            for (CommandResolver resolver : resolvers) {
                shellServer.registerCommandResolver(resolver);
            }

            shellServer.listen(new BindHandler(isBindRef));
            if (!isBind()) {
                throw new IllegalStateException("Arthas failed to bind telnet or http port! Telnet port: "
                        + String.valueOf(configure.getTelnetPort()) + ", http port: "
                        + String.valueOf(configure.getHttpPort()));
            }

            //http api session manager
            sessionManager = new SessionManagerImpl(options, shellServer.getCommandManager(), shellServer.getJobController());
            //http api handler
            httpApiHandler = new HttpApiHandler(historyManager, sessionManager);

            logger().info("as-server listening on network={};telnet={};http={};timeout={};", configure.getIp(),
                    configure.getTelnetPort(), configure.getHttpPort(), options.getConnectionTimeout());

            // 异步回报启动次数
            if (configure.getStatUrl() != null) {
                logger().info("arthas stat url: {}", configure.getStatUrl());
            }
            UserStatUtil.setStatUrl(configure.getStatUrl());
            UserStatUtil.setAgentId(configure.getAgentId());
            UserStatUtil.arthasStart();

            try {
                SpyAPI.init();
            } catch (Throwable e) {
                // ignore
            }

            logger().info("as-server started in {} ms", System.currentTimeMillis() - start);
        } catch (Throwable e) {
            logger().error("Error during start as-server", e);
            destroy();
            throw e;
        }
    }

bind方法主要是启动AgentServer，若有设置tunnelServer则初始化tunnelClient，然后创建ShellServerImpl，对于有设置telnetPort的则注册HttpTelnetTermServer，对于有设置httpPort的则注册HttpTermServer，然后执行shellServer.listen，UserStatUtil.arthasStart()，最后执行SpyAPI.init()

destroy

    public void destroy() {
        if (shellServer != null) {
            shellServer.close();
            shellServer = null;
        }
        if (sessionManager != null) {
            sessionManager.close();
            sessionManager = null;
        }
        if (this.httpSessionManager != null) {
            httpSessionManager.stop();
        }
        if (timer != null) {
            timer.cancel();
        }
        if (this.tunnelClient != null) {
            try {
                tunnelClient.stop();
            } catch (Throwable e) {
                logger().error("stop tunnel client error", e);
            }
        }
        if (executorService != null) {
            executorService.shutdownNow();
        }
        if (transformerManager != null) {
            transformerManager.destroy();
        }
        if (classLoaderInstrumentTransformer != null) {
            instrumentation.removeTransformer(classLoaderInstrumentTransformer);
        }
        // clear the reference in Spy class.
        cleanUpSpyReference();
        shutdownWorkGroup();
        UserStatUtil.destroy();
        if (shutdown != null) {
            try {
                Runtime.getRuntime().removeShutdownHook(shutdown);
            } catch (Throwable t) {
                // ignore
            }
        }
        logger().info("as-server destroy completed.");
        if (loggerContext != null) {
            loggerContext.stop();
        }
    }

destroy方法执行shellServer.close()、sessionManager.close()、httpSessionManager.stop()、timer.cancel()、tunnelClient.stop()、executorService.shutdownNow()、transformerManager.destroy()、instrumentation.removeTransformer(classLoaderInstrumentTransformer)、cleanUpSpyReference()、shutdownWorkGroup()、UserStatUtil.destroy()、Runtime.getRuntime().removeShutdownHook、loggerContext.stop()

小结

ArthasBootstrap的构造器执行initFastjson、initSpy、initArthasEnvironment、LogUtil.initLogger(arthasEnvironment)、enhanceClassLoader、initBeans、bind，最后注册shutdownHook来执行destroy方法。