文章目录
- attach JVM
- agent
- **ArthasBootstrap**
arthas-core的启动可以从上一篇做参考
参考 pom,即启动是调用的 Arthas 的 main 方法
attach JVM
JVM提供了 Java Attach 功能,能够让客户端与目标JVM进行通讯从而获取JVM运行时的数据,甚至可以通过Java Attach 加载自定义的代理工具,实现AOP、运行时class热更新等功能。
private void attachAgent(Configure configure) throws Exception {
VirtualMachineDescriptor virtualMachineDescriptor = null;
for (VirtualMachineDescriptor descriptor : VirtualMachine.list()) {
String pid = descriptor.id();
if (pid.equals(Long.toString(configure.getJavaPid()))) {
virtualMachineDescriptor = descriptor;
break;
}
}
VirtualMachine virtualMachine = null;
try {
if (null == virtualMachineDescriptor) { // 使用 attach(String pid) 这种方式
virtualMachine = VirtualMachine.attach("" + configure.getJavaPid());
} else {
virtualMachine = VirtualMachine.attach(virtualMachineDescriptor);
}
……
try {
virtualMachine.loadAgent(arthasAgentPath,
configure.getArthasCore() + ";" + configure.toString());
} catch (IOException e) {
}
VirtualMachine.list() 相当于 jps 的功能:
attach是依靠这条代码:
virtualMachine = VirtualMachine.attach(virtualMachineDescriptor);
之后就是 loadAgent 并传入 core 和 configure 参数。
agent
agent 的代码很简单,只有2个类:
核心就是 AgentBootstrap ,对于 javaagent来说核心的启动入口:
public static void premain(String args, Instrumentation inst) {
main(args, inst);
}
public static void agentmain(String args, Instrumentation inst) {
main(args, inst);
}
神奇不,在 arthas-core 里传入的 -core 参数实际上是透传给agent的。整的很绕。 通过 bind 方法进行线程绑定,这一步和 arthas-boot 很像。
private static synchronized void main(String args, final Instrumentation inst) {
// 尝试判断arthas是否已在运行,如果是的话,直接就退出
try {
Class.forName("java.arthas.SpyAPI"); // 加载不到会抛异常
if (SpyAPI.isInited()) {
ps.println("Arthas server already stared, skip attach.");
ps.flush();
return;
}
} catch (Throwable e) {
// ignore
}
try {
ps.println("Arthas server agent start...");
// 传递的args参数分两个部分:arthasCoreJar路径和agentArgs, 分别是Agent的JAR包路径和期望传递到服务端的参数
if (args == null) {
args = "";
}
args = decodeArg(args);
String arthasCoreJar;
final String agentArgs;
int index = args.indexOf(';');
if (index != -1) {
arthasCoreJar = args.substring(0, index);
agentArgs = args.substring(index);
} else {
arthasCoreJar = "";
agentArgs = args;
}
File arthasCoreJarFile = new File(arthasCoreJar);
if (!arthasCoreJarFile.exists()) {
ps.println("Can not find arthas-core jar file from args: " + arthasCoreJarFile);
// try to find from arthas-agent.jar directory
CodeSource codeSource = AgentBootstrap.class.getProtectionDomain().getCodeSource();
if (codeSource != null) {
try {
File arthasAgentJarFile = new File(codeSource.getLocation().toURI().getSchemeSpecificPart());
arthasCoreJarFile = new File(arthasAgentJarFile.getParentFile(), ARTHAS_CORE_JAR);
if (!arthasCoreJarFile.exists()) {
ps.println("Can not find arthas-core jar file from agent jar directory: " + arthasAgentJarFile);
}
} catch (Throwable e) {
ps.println("Can not find arthas-core jar file from " + codeSource.getLocation());
e.printStackTrace(ps);
}
}
}
if (!arthasCoreJarFile.exists()) {
return;
}
/**
* Use a dedicated thread to run the binding logic to prevent possible memory leak. #195
*/
final ClassLoader agentLoader = getClassLoader(inst, arthasCoreJarFile);
Thread bindingThread = new Thread() {
@Override
public void run() {
try {
bind(inst, agentLoader, agentArgs);
} catch (Throwable throwable) {
throwable.printStackTrace(ps);
}
}
};
bindingThread.setName("arthas-binding-thread");
bindingThread.start();
bindingThread.join();
} catch (Throwable t) {
t.printStackTrace(ps);
try {
if (ps != System.err) {
ps.close();
}
} catch (Throwable tt) {
// ignore
}
throw new RuntimeException(t);
}
}
ArthasBootstrap
bind 有调用了 core 里面 ArthasBootstrap.getInstance
private static void bind(Instrumentation inst, ClassLoader agentLoader, String args) throws Throwable {
/**
* <pre>
* ArthasBootstrap bootstrap = ArthasBootstrap.getInstance(inst);
* </pre>
*/
Class<?> bootstrapClass = agentLoader.loadClass(ARTHAS_BOOTSTRAP);
Object bootstrap = bootstrapClass.getMethod(GET_INSTANCE, Instrumentation.class, String.class).invoke(null, inst, args);
boolean isBind = (Boolean) bootstrapClass.getMethod(IS_BIND).invoke(bootstrap);
if (!isBind) {
String errorMsg = "Arthas server port binding failed! Please check $HOME/logs/arthas/arthas.log for more details.";
ps.println(errorMsg);
throw new RuntimeException(errorMsg);
}
ps.println("Arthas server already bind.");
}
而在 ArthasBootstrap中 我们用的 terminal,也就是 ShellServer, 就在 6. start agent server
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);
}
ShellServerImpl 的 bind 这段实现中,BuiltinCommandPack 完成了命名的声明并与 cli 输入内容进行命名绑定。并用 Netty 开启server。
/**
* Bootstrap arthas server
*
* @param configure 配置信息
* @throws IOException 服务器启动失败
*/
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;
}
}
参考:
https://blog.csdn.net/tianjindong0804/article/details/128423819