官方文档
https://arthas.aliyun.com/doc/trace.html
redefine
加载外部的.class文件，redefine jvm已加载的类(reset指令无效，退出arthas之后会自动还原代码)。
- redefine的class不能修改、添加、删除类的field和method，包括方法参数、方法名称及返回值
- 如果mc失败(使用lombok容易mc失败)，可以在本地开发环境编译好class文件，上传到目标系统，使用redefine热加载class
- 目前redefine 和watch/trace/jad/tt等命令冲突，以后重新实现redefine功能会解决此问题
- 正在跑的函数，没有退出不能生效
使用方式
方法1
本地把新代码改好之后，复制java文本到服务器；
使用mc XXX.java做内存编译；
最后redefine XXX.class
方法2（推荐）
本地改好代码，本地编译成class文件；
上传class文件到服务器；
最后redefine XXX.class
方法3（base64小技巧—Mac自带base64指令）
本地改好代码并编译成class文件；
base64 < Test.class > result.txt； //base64编码
把上一步的文本粘贴到服务器；
base64 -d < result.txt > Test.class //base64解码
最后redefine XXX.class
方法4（拿不到源码）
先反编译class拿到源码：jad com.test.MyController；
修改源码；
编译源码：mc MyController.java
最后redefine XXX.class
mc
Memory Compiler。eg：mc /tmp/Test.java
跟jvm自带的编译器不同，无需考虑import引入的第三方类，mc会自动从当前jvm中找。
如果提示"line: 31 , message: cannot find symbol"，可以指定类加载器：
mc --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader /home/xiaoju/OtherController.java
但是如果代码中使用了lombok等编译器插件，线上mc是搞不定的，只能IDEA编译好class文件并上传。
Java多版本的坑
springboot启动使用了openjdk版本(功能阉割，没有tool.jar包)，而arthas默认使用$JAVA_HOME的版本启动(可以在/usr/local/jdk1.8.0_65/bin/java -jar arthas-boot.jar更换jdk版本)，两个版本不一致，容易出现各种问题：jad失败，mc失败，redefine失败
trace
网上案例
https://mp.weixin.qq.com/s/BTSGx7kyV2qtIQYOQil6MA
trace作用
trace 命令能主动搜索 class-pattern／method-pattern下，每个方法的耗时
从springmvc开始
[arthas@24851]$ trace org.springframework.web.servlet.DispatcherServlet *
`---ts=2021-01-01 21:25:12;thread_name=http-nio-8888-exec-1;id=14f;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@41627979
`---[5708.279269ms] org.springframework.web.servlet.DispatcherServlet:doService()
+---[0.012965ms] org.apache.commons.logging.Log:isDebugEnabled() #889
+---[1.29531ms] org.springframework.web.util.WebUtils:isIncludeRequest() #898
+---[0.015721ms] org.springframework.web.servlet.DispatcherServlet:getWebApplicationContext() #910
+---[min=0.011911ms,max=0.053343ms,total=0.079159ms,count=3] javax.servlet.http.HttpServletRequest:setAttribute() #95
+---[0.011699ms] javax.servlet.http.HttpServletRequest:setAttribute() #911
+---[0.011377ms] javax.servlet.http.HttpServletRequest:setAttribute() #912
+---[0.08051ms] org.springframework.web.servlet.DispatcherServlet:getThemeSource() #913
| `---[0.057805ms] org.springframework.web.servlet.DispatcherServlet:getThemeSource()
| +---[0.008661ms] org.springframework.web.servlet.DispatcherServlet:getWebApplicationContext() #782
| `---[0.009609ms] org.springframework.web.servlet.DispatcherServlet:getWebApplicationContext() #95
+---[0.061322ms] org.springframework.web.servlet.FlashMapManager:retrieveAndUpdate() #916
+---[0.030471ms] org.springframework.web.servlet.FlashMap:<init>() #920
+---[0.011417ms] javax.servlet.http.HttpServletRequest:setAttribute() #921
+---[5706.387178ms] org.springframework.web.servlet.DispatcherServlet:doDispatch() #925
| `---[5706.354539ms] org.springframework.web.servlet.DispatcherServlet:doDispatch()
| +---[0.016314ms] org.springframework.web.context.request.async.WebAsyncUtils:getAsyncManager() #953
| +---[0.105785ms] org.springframework.web.servlet.DispatcherServlet:checkMultipart() #960
| | `---[0.066694ms] org.springframework.web.servlet.DispatcherServlet:checkMultipart()
| | `---[0.049131ms] org.springframework.web.multipart.MultipartResolver:isMultipart() #1117
| +---[7.168809ms] org.springframework.web.servlet.DispatcherServlet:getHandler() #964
| | `---[7.064781ms] org.springframework.web.servlet.DispatcherServlet:getHandler()
| | +---[min=0.012263ms,max=0.076131ms,total=0.088394ms,count=2] org.apache.commons.logging.Log:isTraceEnabled() #1184
| | `---[min=2.954988ms,max=3.884794ms,total=6.839782ms,count=2] org.springframework.web.servlet.HandlerMapping:getHandler() #1188
| +---[0.012873ms] org.springframework.web.servlet.HandlerExecutionChain:getHandler() #971
| +---[0.328712ms] org.springframework.web.servlet.DispatcherServlet:getHandlerAdapter() #95
| | `---[0.261909ms] org.springframework.web.servlet.DispatcherServlet:getHandlerAdapter()
| | +---[0.081783ms] org.apache.commons.logging.Log:isTraceEnabled() #1225
| | `---[0.082228ms] org.springframework.web.servlet.HandlerAdapter:supports() #1228
| +---[0.020417ms] javax.servlet.http.HttpServletRequest:getMethod() #974
| +---[0.005684ms] org.springframework.web.servlet.HandlerExecutionChain:getHandler() #977
| +---[0.029239ms] org.springframework.web.servlet.HandlerAdapter:getLastModified() #95
| +---[0.013915ms] org.apache.commons.logging.Log:isDebugEnabled() #978
| +---[0.039199ms] org.springframework.web.context.request.ServletWebRequest:<init>() #981
| +---[0.154737ms] org.springframework.web.context.request.ServletWebRequest:checkNotModified() #95
| +---[23.383363ms] org.springframework.web.servlet.HandlerExecutionChain:applyPreHandle() #986
| | `---[1.030624ms] org.springframework.web.servlet.DispatcherServlet:getHandler()
| | +---[min=0.014526ms,max=0.046654ms,total=0.06118ms,count=2] org.apache.commons.logging.Log:isTraceEnabled() #1184
| | `---[min=0.372255ms,max=0.503339ms,total=0.875594ms,count=2] org.springframework.web.servlet.HandlerMapping:getHandler() #1188
| +---[0.006063ms] org.springframework.web.servlet.HandlerExecutionChain:getHandler() #991
| +---[5670.005058ms] org.springframework.web.servlet.HandlerAdapter:handle() #95
| +---[0.018495ms] org.springframework.web.context.request.async.WebAsyncManager:isConcurrentHandlingStarted() #993
| +---[0.070981ms] org.springframework.web.servlet.DispatcherServlet:applyDefaultViewName() #997
| | `---[0.015724ms] org.springframework.web.servlet.DispatcherServlet:applyDefaultViewName()
| +---[0.063922ms] org.springframework.web.servlet.HandlerExecutionChain:applyPostHandle() #998
| +---[2.999835ms] org.springframework.web.servlet.DispatcherServlet:processDispatchResult() #1008
| | `---[2.943566ms] org.springframework.web.servlet.DispatcherServlet:processDispatchResult()
| | +---[0.018672ms] org.apache.commons.logging.Log:isDebugEnabled() #1075
| | +---[0.015961ms] org.springframework.web.context.request.async.WebAsyncUtils:getAsyncManager() #1081
| | +---[0.016024ms] org.springframework.web.context.request.async.WebAsyncManager:isConcurrentHandlingStarted() #95
| | `---[2.797852ms] org.springframework.web.servlet.HandlerExecutionChain:triggerAfterCompletion() #1087
| `---[0.022344ms] org.springframework.web.context.request.async.WebAsyncManager:isConcurrentHandlingStarted() #1018
+---[0.011955ms] org.springframework.web.context.request.async.WebAsyncUtils:getAsyncManager() #928
`---[0.010813ms] org.springframework.web.context.request.async.WebAsyncManager:isConcurrentHandlingStarted() #95
stack
很多时候我们都知道一个方法被执行，但这个方法被执行的路径非常多，或者你根本就不知道这个方法是从那里被执行了，此时你需要的是 stack 命令。
[arthas@96485]$ stack com.wujie.mms.controller.consumer.v2.CShopGoodsController one
Press Q or Ctrl+C to abort.
Affect(class count: 2 , method count: 2) cost in 209 ms, listenerId: 2
ts=2021-01-01 21:47:27;thread_name=http-nio-8888-exec-4;id=82;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@20a10c62
@com.wujie.mms.controller.consumer.v2.CShopGoodsController.one()
at com.wujie.mms.controller.consumer.v2.CShopGoodsController$$FastClassBySpringCGLIB$$2ef83cf7.invoke(<generated>:-1)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
at org.springframework.validation.beanvalidation.MethodValidationInterceptor.invoke(MethodValidationInterceptor.java:119)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:88)
at com.cxyx.common.controller.aspect.ControllerAspect.aroundController(ControllerAspect.java:67)
at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-2)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633)
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:174)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
at com.wujie.mms.controller.consumer.v2.CShopGoodsController$$EnhancerBySpringCGLIB$$d863466d.one(<generated>:25)
at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-2)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:95)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:981)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:873)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:858)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
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:52)
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.CorsFilter.doFilterInternal(CorsFilter.java:96)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
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:200)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
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:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:798)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
watch
让你能方便的观察到指定方法的调用情况。能观察到的范围为：返回值、抛出异常、入参，通过编写 OGNL 表达式进行对应变量的查看。
tt
[arthas@99564]$ tt -t com.wujie.mms.controller.consumer.v2.CShopGoodsController one
Press Q or Ctrl+C to abort.
Affect(class count: 2 , method count: 2) cost in 71 ms, listenerId: 2
INDEX TIMESTAMP COST(ms) IS-RET IS-EXP OBJECT CLASS METHOD
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1000 2021-01-01 23:53:15 174.913883 true false 0x749f61a3 CShopGoodsController one
1001 2021-01-01 23:53:15 490.828957 true false 0xcf3d7688 CShopGoodsController$$EnhancerBySpringCGLIB$$2 one
e74d068
1002 2021-01-01 23:53:22 11.459477 true false 0x749f61a3 CShopGoodsController one
1003 2021-01-01 23:53:22 17.091497 true false 0xcf3d7688 CShopGoodsController$$EnhancerBySpringCGLIB$$2 one
e74d068
1004 2021-01-01 23:53:35 11.739118 true false 0x749f61a3 CShopGoodsController one
1005 2021-01-01 23:53:35 14.276896 true false 0xcf3d7688 CShopGoodsController$$EnhancerBySpringCGLIB$$2 one
e74d068
