[JVM]Java生产环境下性能监控与调优详解_Btrace

本章关键词：BTrace、拦截、注意事项

一、入门

1.做什么的？

• 可以在应用程序不重启，不修改的情况下，正在运行的情况下，动态的修改字节码，达到监控调试的目的
• 可以动态的向目标应用程序的字节码注入追踪代码
• 用到的技术

JavaComplierApi、JVMTI、Agent、Instrumentation+ASM

2.安装

• 到官网中下载相应版本
• 新建环境变量BTRACE_HOME，添加Path:%BTRACE_HOME%\bin

环境变量的添加请自行百度

• 两种运行脚本方式

1. JVisualVM中添加Btrace插件（参见上一章），添加classpath

2.使用命令行btrace

3.使用详解

• 代码示例
  btrace需要引入三个jar，就是下载的btrace程序中，build目录下的三个

   

  

  jar包.png

引入jar包

        
            com.sun.btrace
            btrace-boot
            1.3.11
            jar
            system
            D:/btrace-bin-1.3.11/build/btrace-boot.jar
        

        
            com.sun.btrace
            btrace-agent
            1.3.11
            jar
            system
            D:/btrace-bin-1.3.11/build/btrace-agent.jar
        
        
            com.sun.btrace
            btrace-client
            1.3.11
            jar
            system
            D:/btrace-bin-1.3.11/build/btrace-client.jar
        

将要被拦截的代码

package com.qinxianyun.monitor_tuning.chapter4;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author Qinxianyun
 * @version V1.0
 * @time 2018/7/21.12:50
 * @description 演示btrace
 */
@RestController
@RequestMapping("ch4")
public class Ch4Controller {
    @RequestMapping("/arg1")
    public String arg1(@RequestParam("name")String name){
        return "hello," + name;
    }
}

btrace脚本（脚本和代码没有必要关联性，脚本可以随便写在哪里，没有必要写在方法的一个项目里面）

package com.qinxianyun.monitor_tuning.chapter4;

import com.sun.btrace.AnyType;
import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.*;

@BTrace
public class PrintArgSimple {
   
    @OnMethod(
            clazz = "com.qinxianyun.monitor_tuning.chapter4.Ch4Controller",
            method = "arg1",
            location = @Location(Kind.ENTRY)
    )
    public static void anyRead(@ProbeClassName String pcn, @ProbeMethodName String pmn, AnyType[] args){
        BTraceUtils.printArray(args);
        BTraceUtils.println(pcn + "," + pmn);
        BTraceUtils.println();
    }
}

@OnMethod表示我们要拦截哪个类的哪个方法，在什么时候进行拦截
Kind.ENTRY表示在入口的时候拦截（也就是一进入方法的时候）
@param pcn 拦截方法类的类名
@param pmn 拦截方法的方法名
@param args 参数

• 进入到btrace脚本的目录下

   

  

  进入目录.png

• 查看进程id

   

  

  查看进程id.png

• 运行脚本文件

   

  

  运行中.png

• 浏览器中输入http://localhost:8080/ch4/arg1?name=qinxianyun
  出现如下处理结果

  

  处理结果.png

   

• Java VisualVM打开btrace（需要已经安装了插件，详情见上一章）

   

  

  vm打开btrace.png

   

  

  界面详解.png

   

  

  输出.png

二、拦截构造函数、同名函数

1.拦截方法（普通方法、构造方法、同名方法）

• 普通方法 @OnMethod(clazz=" ",method=" ")

参考上面的例子

• 构造函数@OnMethod(clazz=" ",method="")

因为构造函数在字节码层面是叫init，所以用

@RequestMapping("/constructor")
    public User arg1(User user){
        return user;
    }

package com.qinxianyun.monitor_tuning.chapter2;

/**
 * @author Qinxianyun
 * @version V1.0
 * @time 2018/7/15.14:52
 * @description 用户实体
 */
public class User {
    private int id;

    private String name;

    public User(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

package com.qinxianyun.monitor_tuning.chapter4;

import com.sun.btrace.AnyType;
import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.BTrace;
import com.sun.btrace.annotations.OnMethod;
import com.sun.btrace.annotations.ProbeClassName;
import com.sun.btrace.annotations.ProbeMethodName;

@BTrace
public class PrintConstructor {

    @OnMethod(
            clazz = "com.qinxianyun.monitor_tuning.chapter2.User",
            method = ""
    )
    public static void anyRead(@ProbeClassName String pcn, @ProbeMethodName String pmn, AnyType[] args){
        BTraceUtils.println(pcn + "," + pmn);
        BTraceUtils.printArray(args);
        BTraceUtils.println();
    }
}

运行结果.png

• 同名方法（用参数区分）

@RequestMapping("/same1")
    public String same(@RequestParam("name")String name){
        return "hello," + name;
    }

    @RequestMapping("/same2")
    public String same(@RequestParam("name")String name,@RequestParam("id")int id){
        return "hello," + name + "," +id;
    }

package com.qinxianyun.monitor_tuning.chapter4;

import com.sun.btrace.AnyType;
import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.BTrace;
import com.sun.btrace.annotations.OnMethod;
import com.sun.btrace.annotations.ProbeClassName;
import com.sun.btrace.annotations.ProbeMethodName;

@BTrace
public class PrintSame {
    @OnMethod(
            clazz = "com.qinxianyun.monitor_tuning.chapter4.Ch4Controller",
            method = "same"
    )
    public static void anyRead(@ProbeClassName String pcn, @ProbeMethodName String pmn, String name ,int id){
        BTraceUtils.println(pcn + "," + pmn + "," + name + "," + id);
        BTraceUtils.println();
    }
}

拦截重载的方法，是根据参数的类型区分的，脚本中的名字可以和代码中参数名不一致

运行结果：

 

运行结果1.png

三、拦截返回值、异常行号

1.拦截时机

• Kind.ENTRY : 入口，默认值

参考第一个例子

• Kind.RETURN ： 返回

package com.qinxianyun.monitor_tuning.chapter4;

import com.sun.btrace.AnyType;
import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.*;

@BTrace
public class PrintReturn {
    @OnMethod(
            clazz = "com.qinxianyun.monitor_tuning.chapter4.Ch4Controller",
            method = "arg1",
            location = @Location(Kind.RETURN)
    )
    public static void anyRead(@ProbeClassName String pcn, @ProbeMethodName String pmn, @Return AnyType result){
        BTraceUtils.println(pcn + "," + pmn + "," + result);
        BTraceUtils.println();
    }
}

• Kind.THROW ： 异常

package com.qinxianyun.monitor_tuning.chapter4;

import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.*;

@BTrace
public class PrintOnThrow {
    @TLS
    static Throwable currentException;

    @OnMethod(
            clazz = "java.lang.Throwable",
            method = ""
    )
    public static void onthrow(@Self Throwable self){//new Throwable()
        currentException = self;
    }

    @OnMethod(
            clazz = "java.lang.Throwable",
            method = ""
    )
    public static void onthrow1(@Self Throwable self,String s){//new Throwable(String msg)
        currentException = self;
    }

    @OnMethod(
            clazz = "java.lang.Throwable",
            method = ""
    )
    public static void onthrow1(@Self Throwable self,String s,Throwable cause){//new Throwable(String msg,Throwable cause)
        currentException = self;
    }

    @OnMethod(
            clazz = "java.lang.Throwable",
            method = ""
    )
    public static void onthrow2(@Self Throwable self,Throwable cause){//new Throwable(Throwable cause)
        currentException = self;
    }

    @OnMethod(
            clazz = "java.lang.Throwable",
            method = "",
            location = @Location(Kind.RETURN)
    )
    public static void onthrowreturn(){
        if (currentException != null){
            BTraceUtils.Threads.jstack(currentException);
            BTraceUtils.println("========================");
            currentException = null;
        }
    }
}

• Kind.Line ：行

package com.qinxianyun.monitor_tuning.chapter4;

import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.*;

@BTrace
public class PrintLine {
    @OnMethod(
            clazz = "com.qinxianyun.monitor_tuning.chapter4.Ch4Controller",
            location = @Location(value = Kind.LINE,line = 41)
    )
    public static void anyRead(@ProbeClassName String pcn,@ProbeMethodName String pmn,int line){
        BTraceUtils.println(pcn + "," + pmn + "," + line);
        BTraceUtils.println();
    }
}

四、拦截复杂参数、环境变量、正则匹配拦截

1.拦截this、入参、返回

• this：@Self
• 入参：可以用AnyType，也可以用真实类型，同名的用真实的
• 返回：@Return

2.获取对象的值

• 简单类型：直接获取
• 复杂类型：反射，类名+属性名

package com.qinxianyun.monitor_tuning.chapter4;

import com.qinxianyun.monitor_tuning.chapter2.User;
import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.*;

import java.lang.reflect.Field;

@BTrace
public class PrintArgComplex {
    @OnMethod(
            clazz = "com.qinxianyun.monitor_tuning.chapter4.Ch4Controller",
            method = "arg2",
            location = @Location(Kind.ENTRY)
    )
    public static void anyRead(@ProbeClassName String pcn, @ProbeMethodName String pmn, User user){
        BTraceUtils.printFields(user);
        Field field2 = BTraceUtils.field("com.qinxianyun.monitor_tuning.chapter2.User","name");
        BTraceUtils.println(BTraceUtils.get(field2,user));
        BTraceUtils.println(pcn + "," + pmn);
        BTraceUtils.println();
    }
}

 

 

注意：

复杂类型.png

 

引用的需要加上-cp

3.正则表达式

• 拦截任意方法

package com.qinxianyun.monitor_tuning.chapter4;

import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.*;

@BTrace
public class PrintRegex {
    @OnMethod(
            clazz = "com.qinxianyun.monitor_tuning.chapter4.Ch4Controller",
            method = "/.*/"
    )
    public static void anyRead(@ProbeClassName String pcn, @ProbeMethodName String pmn){
        BTraceUtils.println(pcn + "," + pmn);
        BTraceUtils.println();
    }
}

4.打印环境变量

• 打印(输出类似Jinfo命令)

package com.qinxianyun.monitor_tuning.chapter4;

import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.BTrace;

@BTrace
public class PrintJinfo {
    static {
        BTraceUtils.println("System Properties:");
        BTraceUtils.printProperties();
        BTraceUtils.println("VM Flags:");
        BTraceUtils.printVmArguments();
        BTraceUtils.println("OS Enviroment:");
        BTraceUtils.printEnv();
        BTraceUtils.exit();
    }
}

• 输出结果

   

  

  输出.png

注意事项：
1.默认只能本地运行
2.生产环境下可以使用，但是被修改的字节码不会被还原（即使btrace退出）
因此，脚本中不要有太耗系统资源的东西，否则会影响服务器。