Java 诊断工具之 Arthas

1. 安装

1.1 方式一

步骤一：下载 arthas-boot.jar，然后用java -jar的方式启动

curl -O https://arthas.aliyun.com/arthas-boot.jar

步骤二：选择应用 java 进程

$ $ java -jar arthas-boot.jar
* [1]: 35542
  [2]: 71560 math-game.jar

1.2 方式二：使用 as.sh

在 Linux/Unix/Mac 等平台，
curl -L https://arthas.aliyun.com/install.sh | sh

2. 常用命令

2.1 watch

• express 观察表达式，默认值：{params, target, returnObj}
• [x:] 指定输出结果的属性遍历深度，默认为 1，最大值是 4
• 小技巧：若超过 4 层，可指定参数属性(params[0].name})
• -n 2，表示只执行两次

示例：

@Override
public String greeting(User user, String env) {
    System.out.println("greeting run..." + JSON.toJSONString(user) + env);
    return JSON.toJSONString(user) + "; " + env;
}

通用方式：watch com.example.class.method '{params,returnObj,throwExp}' -n 5 -x 3

[arthas@47310]$ watch com.example.concrete.starter.service.impl.GreetServiceImpl greeting '{params,returnObj,throwExp}'  -n 5  -x 3 
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 169 ms, listenerId: 1
method=com.example.concrete.starter.service.impl.GreetServiceImpl.greeting location=AtExit
ts=2023-06-21 16:56:17; [cost=1.690072ms] result=@ArrayList[
    @Object[][
        @User[
            serialVersionUID=@Long[5196056007908280999],
            name=@String[Tinyspot],
            age=@Integer[20],
            status=null,
            salary=null,
            total=null,
            extErrorCode=null,
        ],
        @String[local],
    ],
    @String[{"age":20,"name":"Tinyspot"}; local],
    null,
]

指定参数 params[0]

[arthas@47310]$ watch com.example.concrete.starter.service.impl.GreetServiceImpl greeting '{params[0],returnObj,throwExp}'  -n 5  -x 3 
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 47 ms, listenerId: 6
method=com.example.concrete.starter.service.impl.GreetServiceImpl.greeting location=AtExit
ts=2023-06-21 17:05:26; [cost=0.315678ms] result=@ArrayList[
    @User[
        serialVersionUID=@Long[5196056007908280999],
        name=@String[Tinyspot],
        age=@Integer[20],
        status=null,
        salary=null,
        total=null,
        extErrorCode=null,
    ],
    @String[{"age":20,"name":"Tinyspot"}; local],
    null,
]

[arthas@47310]$ watch com.example.concrete.starter.service.impl.GreetServiceImpl greeting '{params[1],returnObj,throwExp}'  -n 5  -x 3 
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 47 ms, listenerId: 7
method=com.example.concrete.starter.service.impl.GreetServiceImpl.greeting location=AtExit
ts=2023-06-21 17:06:26; [cost=0.279525ms] result=@ArrayList[
    @String[local],
    @String[{"age":20,"name":"Tinyspot"}; local],
    null,
]

指定参数里的属性

[arthas@47310]$ watch com.example.concrete.starter.service.impl.GreetServiceImpl greeting '{params[0].name,returnObj,throwExp}'  -n 5  -x 3
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 49 ms, listenerId: 9
method=com.example.concrete.starter.service.impl.GreetServiceImpl.greeting location=AtExit
ts=2023-06-21 17:13:36; [cost=0.216618ms] result=@ArrayList[
    @String[Tinyspot],
    @String[{"age":20,"name":"Tinyspot"}; local],
    null,
]

[arthas@47310]$ watch com.example.concrete.starter.service.impl.GreetServiceImpl greeting '{params[0].{#this.name},returnObj,throwExp}'  -n 5  -x 3 
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 49 ms, listenerId: 8
method=com.example.concrete.starter.service.impl.GreetServiceImpl.greeting location=AtExit
ts=2023-06-21 17:09:51; [cost=0.287647ms] result=@ArrayList[
    @ArrayList[
        @String[Tinyspot],
    ],
    @String[{"age":20,"name":"Tinyspot"}; local],
    null,
]

2.2 trace

作用：方法内部调用路径，并输出方法路径上的每个节点上耗时

示例：

[arthas@47310]$ trace com.example.concrete.starter.service.impl.GreetServiceImpl greeting  -n 5 --skipJDKMethod false 
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 201 ms, listenerId: 10
`---ts=2023-06-21 17:17:33;thread_name=http-nio-8080-exec-4;id=5b;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@7f79edee
    `---[0.785942ms] com.example.concrete.starter.service.impl.GreetServiceImpl:greeting()
        +---[3.13% 0.024568ms ] java.lang.StringBuilder:<init>() #17
        +---[5.86% min=0.0039ms,max=0.031258ms,total=0.046033ms,count=3] java.lang.StringBuilder:append() #17
        +---[14.19% 0.111553ms ] com.alibaba.fastjson.JSON:toJSONString() #17
        +---[1.53% 0.011997ms ] java.lang.StringBuilder:toString() #17
        +---[19.77% 0.155415ms ] java.io.PrintStream:println() #17
        +---[0.74% 0.005834ms ] java.lang.StringBuilder:<init>() #18
        +---[5.28% 0.041536ms ] com.alibaba.fastjson.JSON:toJSONString() #18
        +---[1.92% min=0.003606ms,max=0.005787ms,total=0.015053ms,count=3] java.lang.StringBuilder:append() #18
        `---[0.55% 0.00435ms ] java.lang.StringBuilder:toString() #18

2.3 反编译文件 - jad

jad com.example.concrete.xxxServiceImpl

3. IDEA 插件

arthas idea

4. Spring Boot 集成 Arthas

<dependency>
    <groupId>com.taobao.arthas</groupId>
    <artifactId>arthas-spring-boot-starter</artifactId>
    <version>${arthas.version}</version>
</dependency>