用arthas轻松排查线上问题

你是否在项目中会碰到以下一些问题：

在代码中打印各种日志来排查，比如方法的入参，出参，及在方法体中打印日志判断走哪行代码
还有你觉得代码没问题，可是运行出现却是以前的bug，感觉代码没修改，或者别人把你修改好之前的代码部署上去了，你想要看线上部署的是不是你修改的最新代码，把包从服务器上下载下来然后再反编译查看
有些接口请求很慢，你想知道这个接口的方法调用链中耗时时间，你以前是不是通过切面去打印每个方法的耗时时间，修改代码，重新部署
当进程CPU飙高或者占用内存较大，你用top命令查看，然后top -H -p x，把十进制转成16进制，然后jstack x | grep -A 10 y命令排查，会觉得有点麻烦
当本地程序运行正常，线上代码运行不正常，你可能需要优化一个class几行代码，在线上看是否会运行正常，重新打包部署，会觉得有点麻烦

其实阿里的线上排查工具arthas就可以解决上述问题

下载地址：https://alibaba.github.io/arthas/arthas-boot.jar

直接执行命令：

java -jar arthas-boot.jar

如果出现中文乱码，需要添加参数 -Dfile.encoding=UTF-8 ：

java  -Dfile.encoding=UTF-8   -jar arthas-boot.jar

直接输入你要连接的进程号：如 4

进入arthas交互界面

现在根据以下代码来进行测试：

package com.htf.smm.controller;

import com.htf.smm.service.SmmIndexSyncService;
import com.htf.smm.service.impl.TestServiceOne;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.repository.query.Param;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.Objects;

@RestController
@RequestMapping("/smm")
public class SmmController {

    @Autowired
    private TestServiceOne testServiceOne;
    
    @RequestMapping("/ycTest")
    public void ycTest(Long time) {
        System.out.println("执行开始，"+time);
        Other other = new Other();
        other.setInfo("其他");
        Coordinate coordinate = new Coordinate();
        coordinate.setX(1);
        coordinate.setY(2);
        coordinate.setOther(other);
        Address address = new Address();
        address.setAddr("昌北");
        address.setCoordinate(coordinate);
        School school = new School();
        school.setName("华东交大");
        school.setAddress(address);
        ParamEntiry paramEntiry = new ParamEntiry();
        paramEntiry.setName("yc");
        paramEntiry.setAge(32);
        paramEntiry.setSchool(school);
        test(paramEntiry);
        System.out.println("执行完毕");
    }

    public ReturnEntity test(ParamEntiry paramEntiry){
        ReturnEntity returnEntity = new ReturnEntity();
        Other other = new Other();
        other.setInfo("其他");
        Coordinate coordinate = new Coordinate();
        coordinate.setX(1);
        coordinate.setY(2);
        coordinate.setOther(other);
        Address address = new Address();
        address.setAddr("昌北");
        address.setCoordinate(coordinate);
        School school = new School();
        school.setName("华东交大");
        school.setAddress(address);
        returnEntity.setSchool(school);
        return returnEntity;
    }
}

package com.htf.smm.controller;

import lombok.Data;

@Data
public class ParamEntiry {
    private  String name;
    private Integer age;
    private School school;
}
@Data
class School{
    private String name;
    private Address address;
}
@Data
class Address{
    private String addr;
    private Coordinate coordinate;
}
@Data
class Coordinate{
    private int x;
    private int y;
    private Other other;
}
@Data
class Other{
    private String info;
}

@Data
public class ReturnEntity {
    private  String name;
    private Integer age;
    private School school;
}

package com.htf.smm.service.impl;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class TestServiceOne {
    private String serviceName = "one";

    @Autowired
    private TestServiceTwo testServiceTwo;
}

package com.htf.smm.service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class TestServiceTwo {
    private String serviceName = "two";

    @Autowired
    private TestServiceThree testServiceThree;
}

package com.htf.smm.service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class TestServiceThree {
    private String serviceName = "three";

    @Autowired
    private TestServiceFour testServiceFour;
}

package com.htf.smm.service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class TestServiceFour {
    private String serviceName = "four";

    @Autowired
    private TestServiceFive testServiceFive;
}

下面来介绍常用的几个命令，watch，trace，stack ，jad，redefine ，thrad

watch命令

参数名称	参数说明
class-pattern	类名表达式匹配
method-pattern	函数名表达式匹配
express	观察表达式，默认值：`{params, target, returnObj}`
condition-express	条件表达式
[b]	在函数调用之前观察
[e]	在函数异常之后观察
[s]	在函数返回之后观察
[f]	在函数结束之后(正常返回和异常返回)观察
[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，最大值是 4

[arthas@9388]$ watch com.htf.smm.controller.SmmController test
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 27 ms, listenerId: 5
method=com.htf.smm.controller.SmmController.test location=AtExit
ts=2023-03-01 15:11:33; [cost=0.0424ms] result=@ArrayList[
    @Object[][isEmpty=false;size=1],
    @SmmController[com.htf.smm.controller.SmmController@59fe5960],
    @ReturnEntity[ReturnEntity(name=null, age=null, school=School(name=华东交大, address=Address(addr=昌北, coordinate=Coordinate(x=1, y=2, other=Other(info=其他)))))],
]

默认返回params，target，returnObj（{params, target, returnObj}）深度为1（-x 1），且在函数结束之后(正常返回和异常返回)（-f）观察，即等于下面这个命令

[arthas@9388]$ watch com.htf.smm.controller.SmmController test "{params, target, returnObj}" -x 1 -f
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 28 ms, listenerId: 7
method=com.htf.smm.controller.SmmController.test location=AtExit
ts=2023-03-01 15:44:01; [cost=0.0398ms] result=@ArrayList[
    @Object[][isEmpty=false;size=1],
    @SmmController[com.htf.smm.controller.SmmController@59fe5960],
    @ReturnEntity[ReturnEntity(name=null, age=null, school=School(name=华东交大, address=Address(addr=昌北, coordinate=Coordinate(x=1, y=2, other=Other(info=其他)))))],
]

@Object[][isEmpty=false;size=1] 为params，为什么是个数组呢？因为参数可能有多个

@SmmController[com.htf.smm.controller.SmmController@59fe5960] 为当前对象

@ReturnEntity[ReturnEntity(name=null, age=null, school=School(name=华东交大, address=Address(addr=昌北, coordinate=Coordinate(x=1, y=2, other=Other(info=其他)))))] 为returnObj

location=AtExit 为在函数结束之后正常返回观察

重要参数-x，默认为1，但是当参数和当前对象的属性有对象引用的时候，我们就需要用到-x，如上命令执行 @SmmController[com.htf.smm.controller.SmmController@59fe5960] 我们无法查看到当前对象内部有什么属性，@Object[][isEmpty=false;size=1]当前参数的具体值

我们设置-x 2试试

[arthas@9388]$ watch com.htf.smm.controller.SmmController test "{params, target, returnObj}" -x 2 -f
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 29 ms, listenerId: 14
method=com.htf.smm.controller.SmmController.test location=AtExit
ts=2023-03-01 16:01:39; [cost=0.0249ms] result=@ArrayList[
    @Object[][
        @ParamEntiry[ParamEntiry(name=yc, age=32, school=School(name=华东交大, address=Address(addr=昌北, coordinate=Coordinate(x=1, y=2, other=Other(info=其他)))))],
    ],
    @SmmController[
        testServiceOne=@TestServiceOne[com.htf.smm.service.impl.TestServiceOne@55111d28],
    ],
    @ReturnEntity[
        name=null,
        age=null,
        school=@School[School(name=华东交大, address=Address(addr=昌北, coordinate=Coordinate(x=1, y=2, other=Other(info=其他))))],
    ],
]

上述所示，就把参数1对应的对象展示出来了，把当前对象中的对象引用展示出来了，把返回对象的引用给展示出来了

注意：-x的最大值为4

重要参数-n，默认是无限次，当线上执行这个接口比较频繁，我们用运维工具可能会频繁去监听打印这个方法相关的信息，很耗服务器资源，而且影响接口响应耗时的时间，当我们为了排查问题，只要获取到一次监听的时候，就可以加-n参数，-n 1表示只执行两次,执行1次后，就会自动退出监听

[arthas@9388]$ watch com.htf.smm.controller.SmmController test "{params, target, returnObj}" -x 2 -f -n 1
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 30 ms, listenerId: 15
method=com.htf.smm.controller.SmmController.test location=AtExit
ts=2023-03-01 16:12:51; [cost=0.0357ms] result=@ArrayList[
    @Object[][
        @ParamEntiry[ParamEntiry(name=yc, age=32, school=School(name=华东交大, address=Address(addr=昌北, coordinate=Coordinate(x=1, y=2, other=Other(info=其他)))))],
    ],
    @SmmController[
        testServiceOne=@TestServiceOne[com.htf.smm.service.impl.TestServiceOne@55111d28],
    ],
    @ReturnEntity[
        name=null,
        age=null,
        school=@School[School(name=华东交大, address=Address(addr=昌北, coordinate=Coordinate(x=1, y=2, other=Other(info=其他))))],
    ],
]
Command execution times exceed limit: 1, so command will exit. You can set it with -n option.

最后一行Command execution times exceed limit: 1, so command will exit. You can set it with -n option.表示执行次数限制为1次，可以通过-n来设置执行的次数

trace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
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

根据耗时"#cost>0"大小匹配如下，耗时是以s为单位的

[arthas@9388]$ trace com.htf.smm.controller.SmmController ycTest "#cost>0"
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 36 ms, listenerId: 27
`---ts=2023-03-02 09:54:37;thread_name=http-nio-8080-exec-2;id=4f;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@1aa6e3c0
    `---[0.3154ms] com.htf.smm.controller.SmmController:ycTest()
        +---[3.01% 0.0095ms ] com.htf.smm.controller.Other:<init>() #31
        +---[1.49% 0.0047ms ] com.htf.smm.controller.Other:setInfo() #32
        +---[1.81% 0.0057ms ] com.htf.smm.controller.Coordinate:<init>() #33
        +---[1.55% 0.0049ms ] com.htf.smm.controller.Coordinate:setX() #34
        +---[1.20% 0.0038ms ] com.htf.smm.controller.Coordinate:setY() #35
        +---[1.30% 0.0041ms ] com.htf.smm.controller.Coordinate:setOther() #36
        +---[1.30% 0.0041ms ] com.htf.smm.controller.Address:<init>() #37
        +---[1.17% 0.0037ms ] com.htf.smm.controller.Address:setAddr() #38
        +---[1.24% 0.0039ms ] com.htf.smm.controller.Address:setCoordinate() #39
        +---[1.17% 0.0037ms ] com.htf.smm.controller.School:<init>() #40
        +---[1.33% 0.0042ms ] com.htf.smm.controller.School:setName() #41
        +---[1.33% 0.0042ms ] com.htf.smm.controller.School:setAddress() #42
        +---[1.24% 0.0039ms ] com.htf.smm.controller.ParamEntiry:<init>() #43
        +---[1.14% 0.0036ms ] com.htf.smm.controller.ParamEntiry:setName() #44
        +---[1.43% 0.0045ms ] com.htf.smm.controller.ParamEntiry:setAge() #45
        +---[1.24% 0.0039ms ] com.htf.smm.controller.ParamEntiry:setSchool() #46
        `---[3.01% 0.0095ms ] com.htf.smm.controller.SmmController:test() #47

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
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:]`	执行次数限制（stack，watch，trace命令用法一致）

根据参数值"params[0].name=='yc'"匹配，用法如下：

[arthas@9388]$ stack com.htf.smm.controller.SmmController test "params[0].name=='yc'"
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 28 ms, listenerId: 37
ts=2023-03-02 10:16:57;thread_name=http-nio-8080-exec-4;id=51;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@1aa6e3c0
    @com.htf.smm.controller.SmmController.test()
        at com.htf.smm.controller.SmmController.ycTest(SmmController.java:47)
        at sun.reflect.GeneratedMethodAccessor55.invoke(null:-1)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:483)
        at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
        at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373)
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589)
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:744)

注意：stack命令和trace命令参数值匹配和耗时大小匹配可以联合使用，如下：

[arthas@9388]$ stack com.htf.smm.controller.SmmController test "params[0].name=='yc'" "#cost>0"
Press Q or Ctrl+C to abort.
Affect(class count: 1 , method count: 1) cost in 38 ms, listenerId: 38
ts=2023-03-02 10:23:37;thread_name=http-nio-8080-exec-6;id=53;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@1aa6e3c0
    @com.htf.smm.controller.SmmController.test()
        at com.htf.smm.controller.SmmController.ycTest(SmmController.java:47)
        at sun.reflect.GeneratedMethodAccessor55.invoke(null:-1)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:483)
        at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
        at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373)
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589)
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:744)

jad命令

lass-pattern	类名表达式匹配
`[c:]`	类所属 ClassLoader 的 hashcode
`[classLoaderClass:]`	指定执行表达式的 ClassLoader 的 class name
[E]	开启正则表达式匹配，默认为通配符匹配

反编译类jad 类路径：

[arthas@9388]$ jad com.htf.smm.controller.SmmController

ClassLoader:
+-sun.misc.Launcher$AppClassLoader@58644d46
  +-sun.misc.Launcher$ExtClassLoader@71c7db30

Location:
/E:/code/htf/htf-parent/htf-damp-parent/htf-damp-smm/target/classes/

       /*
        * Decompiled with CFR.
        *
        * Could not load the following classes:
        *  com.htf.smm.controller.Address
        *  com.htf.smm.controller.Coordinate
        *  com.htf.smm.controller.Other
        *  com.htf.smm.controller.ParamEntiry
        *  com.htf.smm.controller.ReturnEntity
        *  com.htf.smm.controller.School
        *  com.htf.smm.service.impl.TestServiceOne
        */
       package com.htf.smm.controller;

       import com.htf.smm.controller.Address;
       import com.htf.smm.controller.Coordinate;
       import com.htf.smm.controller.Other;
       import com.htf.smm.controller.ParamEntiry;
       import com.htf.smm.controller.ReturnEntity;
       import com.htf.smm.controller.School;
       import com.htf.smm.service.impl.TestServiceOne;
       import org.springframework.beans.factory.annotation.Autowired;
       import org.springframework.web.bind.annotation.RequestMapping;
       import org.springframework.web.bind.annotation.RestController;

       @RestController
       @RequestMapping(value={"/smm"})
       public class SmmController {
           @Autowired
           private TestServiceOne testServiceOne;

           public ReturnEntity test(ParamEntiry paramEntiry) {
               ReturnEntity returnEntity = new ReturnEntity();
               Other other = new Other();
/*54*/         other.setInfo("其他");
               Coordinate coordinate = new Coordinate();
/*56*/         coordinate.setX(1);
/*57*/         coordinate.setY(2);
/*58*/         coordinate.setOther(other);
               Address address = new Address();
/*60*/         address.setAddr("昌北");
/*61*/         address.setCoordinate(coordinate);
               School school = new School();
/*63*/         school.setName("华东交大");
/*64*/         school.setAddress(address);
/*65*/         returnEntity.setSchool(school);
/*66*/         return returnEntity;
           }

           @RequestMapping(value={"/ycTest"})
           public void ycTest(Long time) throws InterruptedException {
/*30*/         System.out.println("执行开始，" + time);
               Other other = new Other();
/*32*/         other.setInfo("其他");
               Coordinate coordinate = new Coordinate();
/*34*/         coordinate.setX(1);
/*35*/         coordinate.setY(2);
/*36*/         coordinate.setOther(other);
               Address address = new Address();
/*38*/         address.setAddr("昌北");
/*39*/         address.setCoordinate(coordinate);
               School school = new School();
/*41*/         school.setName("华东交大");
/*42*/         school.setAddress(address);
               ParamEntiry paramEntiry = new ParamEntiry();
/*44*/         paramEntiry.setName("yc");
/*45*/         paramEntiry.setAge(Integer.valueOf(32));
/*46*/         paramEntiry.setSchool(school);
/*47*/         this.test(paramEntiry);
/*48*/         System.out.println("执行完毕");
           }
       }

Affect(row-cnt:1) cost in 357 ms.

其中有ClassLoader和Location信息，如果把他去掉，加 --source-only 参数，如下所示：

[arthas@9388]$ jad com.htf.smm.controller.SmmController  --source-only
       /*
        * Decompiled with CFR.
        *
        * Could not load the following classes:
        *  com.htf.smm.controller.Address
        *  com.htf.smm.controller.Coordinate
        *  com.htf.smm.controller.Other
        *  com.htf.smm.controller.ParamEntiry
        *  com.htf.smm.controller.ReturnEntity
        *  com.htf.smm.controller.School
        *  com.htf.smm.service.impl.TestServiceOne
        */
       package com.htf.smm.controller;

       import com.htf.smm.controller.Address;
       import com.htf.smm.controller.Coordinate;
       import com.htf.smm.controller.Other;
       import com.htf.smm.controller.ParamEntiry;
       import com.htf.smm.controller.ReturnEntity;
       import com.htf.smm.controller.School;
       import com.htf.smm.service.impl.TestServiceOne;
       import org.springframework.beans.factory.annotation.Autowired;
       import org.springframework.web.bind.annotation.RequestMapping;
       import org.springframework.web.bind.annotation.RestController;

       @RestController
       @RequestMapping(value={"/smm"})
       public class SmmController {
           @Autowired
           private TestServiceOne testServiceOne;

           public ReturnEntity test(ParamEntiry paramEntiry) {
               ReturnEntity returnEntity = new ReturnEntity();
               Other other = new Other();
/*54*/         other.setInfo("其他");
               Coordinate coordinate = new Coordinate();
/*56*/         coordinate.setX(1);
/*57*/         coordinate.setY(2);
/*58*/         coordinate.setOther(other);
               Address address = new Address();
/*60*/         address.setAddr("昌北");
/*61*/         address.setCoordinate(coordinate);
               School school = new School();
/*63*/         school.setName("华东交大");
/*64*/         school.setAddress(address);
/*65*/         returnEntity.setSchool(school);
/*66*/         return returnEntity;
           }

           @RequestMapping(value={"/ycTest"})
           public void ycTest(Long time) throws InterruptedException {
/*30*/         System.out.println("执行开始，" + time);
               Other other = new Other();
/*32*/         other.setInfo("其他");
               Coordinate coordinate = new Coordinate();
/*34*/         coordinate.setX(1);
/*35*/         coordinate.setY(2);
/*36*/         coordinate.setOther(other);
               Address address = new Address();
/*38*/         address.setAddr("昌北");
/*39*/         address.setCoordinate(coordinate);
               School school = new School();
/*41*/         school.setName("华东交大");
/*42*/         school.setAddress(address);
               ParamEntiry paramEntiry = new ParamEntiry();
/*44*/         paramEntiry.setName("yc");
/*45*/         paramEntiry.setAge(Integer.valueOf(32));
/*46*/         paramEntiry.setSchool(school);
/*47*/         this.test(paramEntiry);
/*48*/         System.out.println("执行完毕");
           }
       }

如果不展示行号，加--lineNumber false 参数

[arthas@9388]$ jad com.htf.smm.controller.SmmController  --source-only  --lineNumber false
/*
 * Decompiled with CFR.
 *
 * Could not load the following classes:
 *  com.htf.smm.controller.Address
 *  com.htf.smm.controller.Coordinate
 *  com.htf.smm.controller.Other
 *  com.htf.smm.controller.ParamEntiry
 *  com.htf.smm.controller.ReturnEntity
 *  com.htf.smm.controller.School
 *  com.htf.smm.service.impl.TestServiceOne
 */
package com.htf.smm.controller;

import com.htf.smm.controller.Address;
import com.htf.smm.controller.Coordinate;
import com.htf.smm.controller.Other;
import com.htf.smm.controller.ParamEntiry;
import com.htf.smm.controller.ReturnEntity;
import com.htf.smm.controller.School;
import com.htf.smm.service.impl.TestServiceOne;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping(value={"/smm"})
public class SmmController {
    @Autowired
    private TestServiceOne testServiceOne;

    public ReturnEntity test(ParamEntiry paramEntiry) {
        ReturnEntity returnEntity = new ReturnEntity();
        Other other = new Other();
        other.setInfo("其他");
        Coordinate coordinate = new Coordinate();
        coordinate.setX(1);
        coordinate.setY(2);
        coordinate.setOther(other);
        Address address = new Address();
        address.setAddr("昌北");
        address.setCoordinate(coordinate);
        School school = new School();
        school.setName("华东交大");
        school.setAddress(address);
        returnEntity.setSchool(school);
        return returnEntity;
    }

    @RequestMapping(value={"/ycTest"})
    public void ycTest(Long time) throws InterruptedException {
        System.out.println("执行开始，" + time);
        Other other = new Other();
        other.setInfo("其他");
        Coordinate coordinate = new Coordinate();
        coordinate.setX(1);
        coordinate.setY(2);
        coordinate.setOther(other);
        Address address = new Address();
        address.setAddr("昌北");
        address.setCoordinate(coordinate);
        School school = new School();
        school.setName("华东交大");
        school.setAddress(address);
        ParamEntiry paramEntiry = new ParamEntiry();
        paramEntiry.setName("yc");
        paramEntiry.setAge(Integer.valueOf(32));
        paramEntiry.setSchool(school);
        this.test(paramEntiry);
        System.out.println("执行完毕");
    }
}

反编译类中的方法，如下：

[arthas@9388]$ jad com.htf.smm.controller.SmmController test  --source-only  --lineNumber false
public ReturnEntity test(ParamEntiry paramEntiry) {
    ReturnEntity returnEntity = new ReturnEntity();
    Other other = new Other();
    other.setInfo("其他");
    Coordinate coordinate = new Coordinate();
    coordinate.setX(1);
    coordinate.setY(2);
    coordinate.setOther(other);
    Address address = new Address();
    address.setAddr("昌北");
    address.setCoordinate(coordinate);
    School school = new School();
    school.setName("华东交大");
    school.setAddress(address);
    returnEntity.setSchool(school);
    return returnEntity;
}

retransform命令，结合 jad/mc 命令使用

1、jad 命令反编译，然后可以用其它编译器

[arthas@9388]$ jad com.htf.smm.controller.SmmController   --source-only  --lineNumber false > D:\\\tmp\\\SmmController.java

2、修改源码，修改了日志输出

3、mc 命令来内存编译修改过的代码

[arthas@9388]$ mc  D:\\\tmp\\\SmmController.java -d D:\\\tmp
Memory compiler output:
D:\tmp\com\htf\smm\controller\SmmController.class
Affect(row-cnt:1) cost in 1792 ms.

4、用 retransform 命令加载新的字节码

[arthas@9388]$ retransform D:\\\tmp\\\com\\\htf\\\smm\\\controller\\\SmmController.class
retransform success, size: 1, classes:
com.htf.smm.controller.SmmController

之后调用的时候，日志输出是修改了执行完毕，之前是执行完毕

thread命令

参数名称	参数说明
id	线程 id
[n:]	指定最忙的前 N 个线程并打印堆栈
[b]	找出当前阻塞其他线程的线程
[i `<value>`]	指定 cpu 使用率统计的采样间隔，单位为毫秒，默认值为 200
[--all]	显示所有匹配的线程

我们用它来排查cpu占比很高的问题

得知占比cpu最高的线程的id是81，执行命令thread 81，如下：

[arthas@16256]$ thread 81
"http-nio-8080-exec-1" Id=81 RUNNABLE
    at java.io.FileOutputStream.writeBytes(Native Method)
    at java.io.FileOutputStream.write(FileOutputStream.java:307)
    at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
    at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
    at java.io.PrintStream.write(PrintStream.java:482)
    at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
    at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
    at sun.nio.cs.StreamEncoder.flushBuffer(StreamEncoder.java:104)
    at java.io.OutputStreamWriter.flushBuffer(OutputStreamWriter.java:185)
    at java.io.PrintStream.newLine(PrintStream.java:546)
    at java.io.PrintStream.println(PrintStream.java:807)
    at com.htf.smm.controller.SmmController.test(SmmController.java:66)
    at com.htf.smm.controller.SmmController.ycTest(SmmController.java:46)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:744)

得知在业务代码

at com.htf.smm.controller.SmmController.test(SmmController.java:66)
at com.htf.smm.controller.SmmController.ycTest(SmmController.java:46)中有问题