简介

Arthas 是 Alibaba 开源的 Java 诊断工具。Ta 可以动态跟踪 Java 代码，实时监控 JVM 状态，可以在不中断程序执行的情况下轻松完成 JVM 相关问题排查工作 。支持 JDK 6+，支持 Linux/Mac/Windows。

安装+启动

1、获取 Arthas
wget https://alibaba.github.io/arthas/arthas-boot.jar
2、启动 Arthas
java -jar arthas-boot.jar

成功启动后的效果，如下图：在这里插入图片描述

常用命令

1、stack

输出当前方法被调用的调用路径。很多时候我们都知道一个方法被执行，但是有很多地方调用了它，你并不知道是谁调用了它，此时你需要的是 stack 命令。

参数名称参数说明
class-pattern类名表达式匹配
method-pattern方法名表达式匹配

举个例子，我们想要查看 com.annoroad.alpha.api.controller.RestfulController 类中 detail 方法的调用路径，如下图：
在这里插入图片描述

2、jad

反编译指定已加载类的源码。我们可以通过该命令来确定正在运行的代码是不是最新的代码（因为有的时候，会出现代码发布后，代码没有按预期运行的情况）。

参数名称参数说明
class类名

举个例子，如下：

[arthas@6]$ jad com.annoroad.alpha.api.controller.RestfulController

ClassLoader:
+-org.springframework.boot.loader.LaunchedURLClassLoader@610db97e
  +-sun.misc.Launcher$AppClassLoader@18b4aac2
    +-sun.misc.Launcher$ExtClassLoader@b3b3114

Location:
file:/server.jar!/BOOT-INF/classes!/

       /*
        * Decompiled with CFR.
        *
        * Could not load the following classes:
        *  com.annoroad.alpha.facade.RestfulFacade
        *  com.annoroad.alpha.facade.UserDto
        *  org.slf4j.Logger
        *  org.slf4j.LoggerFactory
        *  org.springframework.web.bind.annotation.RestController
        */
       package com.annoroad.alpha.api.controller;

       import com.annoroad.alpha.api.controller.RestfulController$auxiliary$0NOrXhbf;
       import com.annoroad.alpha.api.controller.RestfulController$auxiliary$95OB8z09;
       import com.annoroad.alpha.api.controller.RestfulController$auxiliary$q2nfGdza;
       import com.annoroad.alpha.api.controller.RestfulController$auxiliary$r7KmaM8n;
       import com.annoroad.alpha.api.controller.RestfulController$auxiliary$rxE4q1Uu;
       import com.annoroad.alpha.api.controller.RestfulController$auxiliary$tipZJ4o0;
       import com.annoroad.alpha.facade.RestfulFacade;
       import com.annoroad.alpha.facade.UserDto;
       import java.lang.reflect.Method;
       import org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.ConstructorInter;
       import org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.EnhancedInstance;
       import org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter;
       import org.slf4j.Logger;
       import org.slf4j.LoggerFactory;
       import org.springframework.web.bind.annotation.RestController;

       @RestController
       public class RestfulController
       implements RestfulFacade,
       EnhancedInstance {
           private static final Logger log;
           private volatile Object _$EnhancedClassField_ws;
           public static volatile /* synthetic */ InstMethodsInter delegate$o54pli0;
           public static volatile /* synthetic */ InstMethodsInter delegate$ggj24u1;
           public static volatile /* synthetic */ ConstructorInter delegate$lpt4b51;
           private static final /* synthetic */ Method cachedValue$U6ueDwbK$4q9ppp1;
           private static final /* synthetic */ Method cachedValue$U6ueDwbK$4pkrst0;
           private static final /* synthetic */ Method cachedValue$U6ueDwbK$0iphd33;
           private static final /* synthetic */ Method cachedValue$U6ueDwbK$b5d02o1;
           private static final /* synthetic */ Method cachedValue$U6ueDwbK$e1rasf2;

           public RestfulController() {
               this(null);
               delegate$lpt4b51.intercept(this, new Object[0]);
           }

           private /* synthetic */ RestfulController(auxiliary.0NOrXhbf nOrXhbf) {
           }

           public UserDto detail(long l) {
               return (UserDto)delegate$o54pli0.intercept(this, new Object[]{l}, new RestfulController$auxiliary$tipZJ4o0(this, l), cachedValue$U6ueDwbK$e1rasf2);
           }

           private /* synthetic */ UserDto detail$original$XaXm2T3V(long id) {
/*18*/         log.info("id : {}", (Object)id);
/*19*/         return UserDto.builder().build();
           }

           public UserDto query(String string, String string2) {
               return (UserDto)delegate$o54pli0.intercept(this, new Object[]{string, string2}, new RestfulController$auxiliary$95OB8z09(this, string, string2), cachedValue$U6ueDwbK$b5d02o1);
           }

           private /* synthetic */ UserDto query$original$XaXm2T3V(String loginName, String userName) {
/*24*/         log.info("loginName: {}, userName: {}", (Object)loginName, (Object)userName);
/*25*/         return UserDto.builder().build();
           }

           public UserDto create(UserDto userDto) {
               return (UserDto)delegate$o54pli0.intercept(this, new Object[]{userDto}, new RestfulController$auxiliary$q2nfGdza(this, userDto), cachedValue$U6ueDwbK$0iphd33);
           }

           private /* synthetic */ UserDto create$original$XaXm2T3V(UserDto userDto) {
/*30*/         log.info("userDto : {}", (Object)userDto);
/*31*/         return userDto;
           }

           public UserDto modify(long l, UserDto userDto) {
               return (UserDto)delegate$o54pli0.intercept(this, new Object[]{l, userDto}, new RestfulController$auxiliary$rxE4q1Uu(this, l, userDto), cachedValue$U6ueDwbK$4pkrst0);
           }

           private /* synthetic */ UserDto modify$original$XaXm2T3V(long id, UserDto userDto) {
/*36*/         log.info("id : {}", (Object)id);
/*37*/         log.info("userDto : {}", (Object)userDto);
/*38*/         return userDto;
           }

           public void close(long l) {
               delegate$o54pli0.intercept(this, new Object[]{l}, new RestfulController$auxiliary$r7KmaM8n(this, l), cachedValue$U6ueDwbK$4q9ppp1);
           }

           private /* synthetic */ void close$original$XaXm2T3V(long id) {
/*43*/         log.info("id : {}", (Object)id);
           }

           /*
            * Enabled aggressive block sorting
            */
           static {
               ClassLoader.getSystemClassLoader().loadClass("org.apache.skywalking.apm.dependencies.net.bytebuddy.dynamic.Nexus").getMethod("initialize", Class.class, Integer.TYPE).invoke(null, RestfulController.class, -745233939);
               cachedValue$U6ueDwbK$4q9ppp1 = RestfulController.class.getMethod("close", Long.TYPE);
               cachedValue$U6ueDwbK$4pkrst0 = RestfulController.class.getMethod("modify", Long.TYPE, UserDto.class);
               cachedValue$U6ueDwbK$0iphd33 = RestfulController.class.getMethod("create", UserDto.class);
               cachedValue$U6ueDwbK$b5d02o1 = RestfulController.class.getMethod("query", String.class, String.class);
               cachedValue$U6ueDwbK$e1rasf2 = RestfulController.class.getMethod("detail", Long.TYPE);
/*14*/         log = LoggerFactory.getLogger(RestfulController.class);
           }

           @Override
           public Object getSkyWalkingDynamicField() {
               return this._$EnhancedClassField_ws;
           }

           @Override
           public void setSkyWalkingDynamicField(Object object) {
               this._$EnhancedClassField_ws = object;
           }

           final /* synthetic */ UserDto modify$original$XaXm2T3V$accessor$U6ueDwbK(long l, UserDto userDto) {
               return this.modify$original$XaXm2T3V(l, userDto);
           }

           final /* synthetic */ UserDto query$original$XaXm2T3V$accessor$U6ueDwbK(String string, String string2) {
               return this.query$original$XaXm2T3V(string, string2);
           }

           final /* synthetic */ UserDto create$original$XaXm2T3V$accessor$U6ueDwbK(UserDto userDto) {
               return this.create$original$XaXm2T3V(userDto);
           }

           final /* synthetic */ UserDto detail$original$XaXm2T3V$accessor$U6ueDwbK(long l) {
               return this.detail$original$XaXm2T3V(l);
           }

           final /* synthetic */ void close$original$XaXm2T3V$accessor$U6ueDwbK(long l) {
               this.close$original$XaXm2T3V(l);
           }
       }

Affect(row-cnt:10) cost in 7334 ms.
3、sc

Search-Class 的简写 ，查看 JVM 已加载的类信息。可以通过该命令来确定类是否被真的加载了（因为有的时候，我们会碰到ClassNotFoundException 或 ClassDefNotFoundException 的异常）。

参数名称参数说明
class-pattern类名表达式匹配
method-pattern方法名表达式匹配
-d输出当前类的详细信息，包括这个类所加载的原始文件来源、类的声明、加载的ClassLoader等详细信息。如果一个类被多个ClassLoader所加载，则会出现多次

举个例子，我们想要搜索 com.annoroad.alpha.api.controller.RestfulController，如下：

[arthas@6]$ sc com.annoroad.alpha.api.controller.RestfulController
com.annoroad.alpha.api.controller.RestfulController
com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c
Affect(row-cnt:2) cost in 23 ms.

搜索详细信息的话，如下：

[arthas@6]$ sc -d com.annoroad.alpha.api.controller.RestfulController
 class-info        com.annoroad.alpha.api.controller.RestfulController
 code-source       file:/server.jar!/BOOT-INF/classes!/
 name              com.annoroad.alpha.api.controller.RestfulController
 isInterface       false
 isAnnotation      false
 isEnum            false
 isAnonymousClass  false
 isArray           false
 isLocalClass      false
 isMemberClass     false
 isPrimitive       false
 isSynthetic       false
 simple-name       RestfulController
 modifier          public
 annotation        org.springframework.web.bind.annotation.RestController
 interfaces        com.annoroad.alpha.facade.RestfulFacade,org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.EnhancedInstance
 super-class       +-java.lang.Object
 class-loader      +-org.springframework.boot.loader.LaunchedURLClassLoader@610db97e
                     +-sun.misc.Launcher$AppClassLoader@18b4aac2
                       +-sun.misc.Launcher$ExtClassLoader@b3b3114
 classLoaderHash   610db97e

 class-info        com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c
 code-source       file:/server.jar!/BOOT-INF/classes!/
 name              com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c
 isInterface       false
 isAnnotation      false
 isEnum            false
 isAnonymousClass  false
 isArray           false
 isLocalClass      false
 isMemberClass     false
 isPrimitive       false
 isSynthetic       false
 simple-name       RestfulController$$EnhancerBySpringCGLIB$$226b455c
 modifier          public
 annotation
 interfaces        org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised,org.springframework.cglib.proxy.Factory
 super-class       +-com.annoroad.alpha.api.controller.RestfulController
                     +-java.lang.Object
 class-loader      +-org.springframework.boot.loader.LaunchedURLClassLoader@610db97e
                     +-sun.misc.Launcher$AppClassLoader@18b4aac2
                       +-sun.misc.Launcher$ExtClassLoader@b3b3114
 classLoaderHash   610db97e

Affect(row-cnt:2) cost in 23 ms.
4、sm

与 sc 类似，sm 是 Search-Method 的简写，查看已加载类的方法信息，如下：

[arthas@6]$ sm com.annoroad.alpha.api.controller.RestfulController
com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c <init>()V
com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c getTargetClass()Ljava/lang/Class;
com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c getSkyWalkingDynamicField()Ljava/lang/Object;
com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c setSkyWalkingDynamicField(Ljava/lang/Object;)V
com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c setCallbacks([Lorg/springframework/cglib/proxy/Callback;)V
com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c CGLIB$SET_STATIC_CALLBACKS([Lorg/springframework/cglib/proxy/Callback;)V
com.annoroad.alpha.api.contro
......
Affect(row-cnt:78) cost in 28 ms.

搜索详细信息的话，如下：

[arthas@6]$ sm -d com.annoroad.alpha.api.controller.RestfulController
 declaring-class   com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c
 constructor-name  <init>
 modifier          public
 annotation
 parameters
 exceptions
 classLoaderHash   610db97e

 declaring-class  com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c
 method-name      getTargetClass
 modifier         final,public
 annotation
 parameters
 return           java.lang.Class
 exceptions
 classLoaderHash  610db97e

 declaring-class  com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c
 method-name      getSkyWalkingDynamicField
 modifier         final,public
 annotation
 parameters
 return           java.lang.Object
 exceptions
 classLoaderHash  610db97e
......
Affect(row-cnt:78) cost in 28 ms.
5、watch

可以监测一个方法的入参和返回值。

参数名称参数说明
class-pattern类名表达式匹配
method-pattern方法名表达式匹配
express观察表达式
condition-express条件表达式
-b在方法调用之前观察
-e在方法异常之后观察
-s在方法返回之后观察
-f在方法结束之后(正常返回和异常返回)观察，默认选项
-E开启正则表达式匹配，默认为通配符匹配
-x指定输出结果的属性遍历深度，默认为 1

举个例子，我们要查看 com.annoroad.alpha.api.controller.RestfulController 类中 detail 方法的出参和返回值，如下：

[arthas@6]$ watch com.annoroad.alpha.api.controller.RestfulController detail {params,returnObj} -x 2
Press Q or Ctrl+C to abort.
Affect(class count: 2 , method count: 2) cost in 702 ms, listenerId: 3
method=com.annoroad.alpha.api.controller.RestfulController.detail location=AtExit
ts=2022-08-04 13:06:03; [cost=1.920253ms] result=@ArrayList[
    @Object[][
        @Long[1],
    ],
    @UserDto[
        id=null,
        loginName=null,
        userName=null,
        password=null,
        email=null,
        mobile=null,
        status=null,
        emailAuth=null,
        remarks=null,
        createTime=null,
        updateTime=null,
    ],
]
method=com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c.detail location=AtExit
ts=2022-08-04 13:06:03; [cost=504.253835ms] result=@ArrayList[
    @Object[][
        @Long[1],
    ],
    @UserDto[
        id=null,
        loginName=null,
        userName=null,
        password=null,
        email=null,
        mobile=null,
        status=null,
        emailAuth=null,
        remarks=null,
        createTime=null,
        updateTime=null,
    ],
]

如果我们要查看异常的话，可以在 {params,returnObj} 里增加 throwExp ，如：{params,returnObj,throwExp}

6、trace

输出方法内部的调用路径，以及路径上每个节点的耗时。

参数名称参数说明
class-pattern类名表达式匹配
method-pattern方法名表达式匹配
express观察表达式
condition-express条件表达式
-E开启正则表达式匹配，默认为通配符匹配
-n命令执行次数
#cost方法执行耗时

举个例子，我们要查看 com.annoroad.alpha.api.controller.RestfulController 类中 detail 方法的调用路径，，以及路径上每个节点的耗时，如下：

[arthas@6]$ trace com.annoroad.alpha.api.controller.RestfulController detail
Press Q or Ctrl+C to abort.
Affect(class count: 2 , method count: 2) cost in 687 ms, listenerId: 7
`---ts=2022-08-04 13:17:57;thread_name=http-nio-20000-exec-3;id=44;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@2ac05a33
    `---[9.918521ms] com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c:detail()
        `---[98.63% 9.782571ms ] org.springframework.cglib.proxy.MethodInterceptor:intercept()
            `---[16.66% 1.629865ms ] com.annoroad.alpha.api.controller.RestfulController:detail()
                +---[1.57% 0.025631ms ] com.annoroad.alpha.api.controller.RestfulController$auxiliary$tipZJ4o0:<init>()
                `---[90.97% 1.482733ms ] org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter:intercept()

如果只想看到耗时大于 1ms 的节点，如下：

[arthas@6]$ trace com.annoroad.alpha.api.controller.RestfulController detail '#cost > 1'
Press Q or Ctrl+C to abort.
Affect(class count: 2 , method count: 2) cost in 632 ms, listenerId: 10
`---ts=2022-08-04 13:21:56;thread_name=http-nio-20000-exec-1;id=42;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@2ac05a33
    `---[3.996851ms] com.annoroad.alpha.api.controller.RestfulController$$EnhancerBySpringCGLIB$$226b455c:detail()
        `---[98.23% 3.926263ms ] org.springframework.cglib.proxy.MethodInterceptor:intercept()
            `---[51.64% 2.027492ms ] com.annoroad.alpha.api.controller.RestfulController:detail()
                +---[0.69% 0.013957ms ] com.annoroad.alpha.api.controller.RestfulController$auxiliary$tipZJ4o0:<init>()
                `---[94.76% 1.921184ms ] org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter:intercept()
7、dashboard

查看当前系统的实时数据面板，这个命令可以全局的查看 JVM 运行状态，例如：内存 和 CPU 占用情况，如下：
在这里插入图片描述

列名说明
IDJava 级别的线程 ID，注意这个 ID 不能跟 jstack 中的 nativeID 一一对应 我们可以通过 thread id 查看线程的堆栈信息
NAME线程名
GROUP线程组名
PRIORITY线程优先级，1~10之间的数字，越大表示优先级越高
STATE线程的状态
CPU%线程消耗的 CPU 占比，采样 100ms，将所有线程在这 100ms 内的 CPU 使用量求和，再算出每个线程的 CPU 使用占比
TIME线程运行总时间，数据格式为 分:秒
INTERRUPTED线程当前的中断位状态
DAEMON是否是 daemon 线程
8、jobs

执行后台异步任务。线上有些问题是偶然发生的，这时就需要使用异步任务，把信息写入文件。

PS：因为还没有用到，所以这里就先不写了，有需要的同学，可以去【参考】中提供的连接地址查看

9、logger

查看 logger 信息，更新 logger level。

PS：因为还没有用到，所以这里就先不写了，有需要的同学，可以去【参考】中提供的连接地址查看

10、redefine

redefine jvm 已加载的类 ，可以在不重启项目的情况下，热更新类。

PS：因为还没有用到，所以这里就先不写了，有需要的同学，可以去【参考】中提供的连接地址查看

参考

# java # jvm # 开发语言
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