本文主要參考慕課網(wǎng)若魚老師課程Java生產(chǎn)環(huán)境下性能監(jiān)控與調(diào)優(yōu)詳解

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本章關(guān)鍵詞：BTrace匀油、攔截、注意事項

一勾笆、入門

1.做什么的肖抱？

• 可以在應(yīng)用程序不重啟郭计，不修改的情況下，正在運行的情況下，動態(tài)的修改字節(jié)碼倚喂，達到監(jiān)控調(diào)試的目的
• 可以動態(tài)的向目標應(yīng)用程序的字節(jié)碼注入追蹤代碼
• 用到的技術(shù)

JavaComplierApi、JVMTI馆铁、Agent榨为、Instrumentation+ASM

2.安裝

• 到官網(wǎng)中下載相應(yīng)版本
• 新建環(huán)境變量BTRACE_HOME，添加Path:%BTRACE_HOME%\bin

環(huán)境變量的添加請自行百度

• 兩種運行腳本方式

1. JVisualVM中添加Btrace插件（參見上一章）啃勉，添加classpath

2.使用命令行btrace <pid> <trace_script>

3.使用詳解

• 代碼示例
  btrace需要引入三個jar忽舟，就是下載的btrace程序中，build目錄下的三個

  
  
  jar包.png

引入jar包

<!--btrace -->
        <dependency>
            <groupId>com.sun.btrace</groupId>
            <artifactId>btrace-boot</artifactId>
            <version>1.3.11</version>
            <type>jar</type>
            <scope>system</scope>
            <systemPath>D:\btrace-bin-1.3.11\build\btrace-boot.jar</systemPath>
        </dependency>

        <dependency>
            <groupId>com.sun.btrace</groupId>
            <artifactId>btrace-agent</artifactId>
            <version>1.3.11</version>
            <type>jar</type>
            <scope>system</scope>
            <systemPath>D:\btrace-bin-1.3.11\build\btrace-agent.jar</systemPath>
        </dependency>
        <dependency>
            <groupId>com.sun.btrace</groupId>
            <artifactId>btrace-client</artifactId>
            <version>1.3.11</version>
            <type>jar</type>
            <scope>system</scope>
            <systemPath>D:\btrace-bin-1.3.11\build\btrace-client.jar</systemPath>
        </dependency>

將要被攔截的代碼

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腳本（腳本和代碼沒有必要關(guān)聯(lián)性淮阐，腳本可以隨便寫在哪里叮阅，沒有必要寫在方法的一個項目里面）

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表示我們要攔截哪個類的哪個方法，在什么時候進行攔截
Kind.ENTRY表示在入口的時候攔截（也就是一進入方法的時候）
@param pcn 攔截方法類的類名
@param pmn 攔截方法的方法名
@param args 參數(shù)

• 進入到btrace腳本的目錄下

  
  
  進入目錄.png

• 查看進程id

  
  
  查看進程id.png

• 運行腳本文件

  
  
  運行中.png

• 瀏覽器中輸入http://localhost:8080/ch4/arg1?name=qinxianyun
  出現(xiàn)如下處理結(jié)果
  

  處理結(jié)果.png

• Java VisualVM打開btrace（需要已經(jīng)安裝了插件泣特，詳情見上一章）

  
  
  vm打開btrace.png
  
  
  界面詳解.png
  
  
  輸出.png

二浩姥、攔截構(gòu)造函數(shù)、同名函數(shù)

1.攔截方法（普通方法状您、構(gòu)造方法勒叠、同名方法）

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

參考上面的例子

• 構(gòu)造函數(shù)@OnMethod(clazz=" ",method="<init>")

因為構(gòu)造函數(shù)在字節(jié)碼層面是叫init兜挨，所以用<init>

@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 用戶實體
 */
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 = "<init>"
    )
    public static void anyRead(@ProbeClassName String pcn, @ProbeMethodName String pmn, AnyType[] args){
        BTraceUtils.println(pcn + "," + pmn);
        BTraceUtils.printArray(args);
        BTraceUtils.println();
    }
}

運行結(jié)果.png

• 同名方法（用參數(shù)區(qū)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();
    }
}

攔截重載的方法，是根據(jù)參數(shù)的類型區(qū)分的眯分，腳本中的名字可以和代碼中參數(shù)名不一致

運行結(jié)果：

運行結(jié)果1.png

三拌汇、攔截返回值、異常行號

1.攔截時機

• Kind.ENTRY : 入口弊决，默認值

參考第一個例子

• 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 ： 異常

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 = "<init>"
    )
    public static void onthrow(@Self Throwable self){//new Throwable()
        currentException = self;
    }

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

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

    @OnMethod(
            clazz = "java.lang.Throwable",
            method = "<init>",
            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();
    }
}

四噪舀、攔截復(fù)雜參數(shù)、環(huán)境變量飘诗、正則匹配攔截

1.攔截this与倡、入?yún)ⅰ⒎祷?/h4>

• this：@Self
• 入?yún)ⅲ嚎梢杂肁nyType昆稿，也可以用真實類型纺座，同名的用真實的
• 返回：@Return

2.獲取對象的值

• 簡單類型：直接獲取
• 復(fù)雜類型：反射，類名+屬性名

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：

復(fù)雜類型.png

引用的需要加上-cp

3.正則表達式

• 攔截任意方法

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.打印環(huán)境變量

• 打印(輸出類似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();
    }
}

• 輸出結(jié)果

  
  
  輸出.png

注意事項：
1.默認只能本地運行
2.生產(chǎn)環(huán)境下可以使用溉潭，但是被修改的字節(jié)碼不會被還原（即使btrace退出）
因此比驻，腳本中不要有太耗系統(tǒng)資源的東西，否則會影響服務(wù)器岛抄。