案例简述
Google开源的Dapper链路追踪组件，并在2010年发表了论文《Dapper, a Large-Scale Distributed Systems Tracing Infrastructure》，这篇文章是业内实现链路追踪的标杆和理论基础，具有非常大的参考价值。目前，链路追踪组件有Google的Dapper，Twitter 的Zipkin，以及阿里的Eagleeye （鹰眼）等，它们都是非常优秀的链路追踪开源组件。本文主要讲述如何在Spring Cloud Sleuth中集成Zipkin。在Spring Cloud Sleuth中集成Zipkin非常的简单，只需要引入相应的依赖和做相关的配置即可。
链路追踪(Dapper)
当业务程序代码在线上运行时，实例A、实例B、实例C，他们直接可能从上到下依次调用，为了能很好的监控程序的调用链路，我们需要对调用链路进行追踪监控。实例的外部可能是通过RPC、HTTP、SOCKET、WEBSERVICE等方式进行调用，内部是方法逻辑依次执行。外部例如http可以通过在头部写入追踪ID进行监控，内部使用threadlocal进行保存上下文关系。｛ThreadLocal变量特殊的地方在于：对变量值的任何操作实际都是对这个变量在线程中的一份copy进行操作，不会影响另外一个线程中同一个ThreadLocal变量的值。｝
环境准备
1、IntelliJ IDEA Community Edition
2、jdk1.8.0_45 64位
配置信息
（路径相关修改为自己的）
1、配置位置：Run/Debug Configurations -> VM options
2、配置内容：-javaagent:E:\itstack\GIT\itstack.org\itstack-demo-agent\itstack-demo-agent-05\target\itstack-demo-agent-05-1.0.0-SNAPSHOT.jar=testargs
代码示例
itstack-demo-agent-05 ├── pom.xml └── src ├── main │ ├── java │ │ └── org.itstack.demo.agent │ │ ├── track │ │ │ ├── TrackContext.java │ │ │ └── TrackManager.java │ │ ├── MyAdvice.java │ │ └── MyAgent.java │ └── resources │ └── META-INF │ └── MANIFEST.MF └── test └── java └── org.itstack.demo.test └── ApiTest.java
TrackContext.java
/** * 博客：http://itstack.org * 论坛：http://bugstack.cn * 公众号：bugstack虫洞栈 ｛获取学习源码｝ * create by fuzhengwei on 2019 */ public class TrackContext { private static final ThreadLocal<String> trackLocal = new ThreadLocal<String>(); public static void clear(){ trackLocal.remove(); } public static String getLinkId(){ return trackLocal.get(); } public static void setLinkId(String linkId){ trackLocal.set(linkId); } }
TrackManager.java
/** * 追踪管控 * 博客：http://itstack.org * 论坛：http://bugstack.cn * 公众号：bugstack虫洞栈 ｛获取学习源码｝ * create by fuzhengwei on 2019 */ public class TrackManager { private static final ThreadLocal<Stack<String>> track = new ThreadLocal<Stack<String>>(); private static String createSpan() { Stack<String> stack = track.get(); if (stack == null) { stack = new Stack<>(); track.set(stack); } String linkId; if (stack.isEmpty()) { linkId = TrackContext.getLinkId(); if (linkId == null) { linkId = "nvl"; TrackContext.setLinkId(linkId); } } else { linkId = stack.peek(); TrackContext.setLinkId(linkId); } return linkId; } public static String createEntrySpan() { String span = createSpan(); Stack<String> stack = track.get(); stack.push(span); return span; } public static String getExitSpan() { Stack<String> stack = track.get(); if (stack == null || stack.isEmpty()) { TrackContext.clear(); return null; } return stack.pop(); } public static String getCurrentSpan() { Stack<String> stack = track.get(); if (stack == null || stack.isEmpty()) { return null; } return stack.peek(); } }
MyAdvice.java
/** * 博客：http://itstack.org * 论坛：http://bugstack.cn * 公众号：bugstack虫洞栈 ｛获取学习源码｝ * create by fuzhengwei on 2019 */ public class MyAdvice { @Advice.OnMethodEnter() public static void enter(@Advice.Origin("#t") String className, @Advice.Origin("#m") String methodName) { String linkId = TrackManager.getCurrentSpan(); if (null == linkId) { linkId = UUID.randomUUID().toString(); TrackContext.setLinkId(linkId); } String entrySpan = TrackManager.createEntrySpan(); System.out.println("链路追踪：" + entrySpan + " " + className + "." + methodName); } @Advice.OnMethodExit() public static void exit(@Advice.Origin("#t") String className, @Advice.Origin("#m") String methodName) { TrackManager.getExitSpan(); } }
MyAgent.java
/** * javaagent * 博客：http://itstack.org * 论坛：http://bugstack.cn * 公众号：bugstack虫洞栈 ｛获取学习源码｝ * create by fuzhengwei on 2019 */ public class MyAgent { //JVM 首先尝试在代理类上调用以下方法 public static void premain(String agentArgs, Instrumentation inst) { System.out.println("基于javaagent链路追踪"); AgentBuilder agentBuilder = new AgentBuilder.Default(); AgentBuilder.Transformer transformer = (builder, typeDescription, classLoader, javaModule) -> { builder = builder.visit( Advice.to(MyAdvice.class) .on(ElementMatchers.isMethod() .and(ElementMatchers.any()).and(ElementMatchers.not(ElementMatchers.nameStartsWith("main"))))); return builder; }; agentBuilder = agentBuilder.type(ElementMatchers.nameStartsWith("org.itstack.demo.test")).transform(transformer).asDecorator(); //监听 AgentBuilder.Listener listener = new AgentBuilder.Listener() { @Override public void onDiscovery(String s, ClassLoader classLoader, JavaModule javaModule, boolean b) { } @Override public void onTransformation(TypeDescription typeDescription, ClassLoader classLoader, JavaModule javaModule, boolean b, DynamicType dynamicType) { System.out.println("onTransformation：" + typeDescription); } @Override public void onIgnored(TypeDescription typeDescription, ClassLoader classLoader, JavaModule javaModule, boolean b) { } @Override public void onError(String s, ClassLoader classLoader, JavaModule javaModule, boolean b, Throwable throwable) { } @Override public void onComplete(String s, ClassLoader classLoader, JavaModule javaModule, boolean b) { } }; agentBuilder.with(listener).installOn(inst); } //如果代理类没有实现上面的方法，那么 JVM 将尝试调用该方法 public static void premain(String agentArgs) { } }
MANIFEST.MF
Manifest-Version: 1.0 Premain-Class: org.itstack.demo.agent.MyAgent Can-Redefine-Classes: true
ApiTest.java
/** * 线程内方法追踪 * 博客：http://itstack.org * 论坛：http://bugstack.cn * 公众号：bugstack虫洞栈 ｛获取学习源码｝ * create by fuzhengwei on 2019 * VM options： * -javaagent:E:\itstack\GIT\itstack.org\itstack-demo-agent\itstack-demo-agent-05\target\itstack-demo-agent-05-1.0.0-SNAPSHOT.jar=testargs */ public class ApiTest { public static void main(String[] args) { //线程一 new Thread(() -> new ApiTest().http_lt1()).start(); //线程二 new Thread(() -> { new ApiTest().http_lt1(); }).start(); } public void http_lt1() { System.out.println("测试结果：hi1"); http_lt2(); } public void http_lt2() { System.out.println("测试结果：hi2"); http_lt3(); } public void http_lt3() { System.out.println("测试结果：hi3"); } }
测试结果
基于javaagent链路追踪 onTransformation：class org.itstack.demo.test.ApiTest 链路追踪：7dfd98e8-c474-461c-87b9-1da3bf6072c2 org.itstack.demo.test.ApiTest.http_lt1 测试结果：hi1 链路追踪：7dfd98e8-c474-461c-87b9-1da3bf6072c2 org.itstack.demo.test.ApiTest.http_lt2 测试结果：hi2 链路追踪：7dfd98e8-c474-461c-87b9-1da3bf6072c2 org.itstack.demo.test.ApiTest.http_lt3 测试结果：hi3 链路追踪：69cdf9d3-1f42-4cf6-8d80-5362dd7ea140 org.itstack.demo.test.ApiTest.http_lt1 测试结果：hi1 链路追踪：69cdf9d3-1f42-4cf6-8d80-5362dd7ea140 org.itstack.demo.test.ApiTest.http_lt2 测试结果：hi2 链路追踪：69cdf9d3-1f42-4cf6-8d80-5362dd7ea140 org.itstack.demo.test.ApiTest.http_lt3 测试结果：hi3 Process finished with exit code 0
