利用btrace在线监控java程序状态

btrace介绍

      下载地址：https://kenai.com/projects/btrace/downloads/directory/releases/

      选择版本进行下载，这里下载的是release-1.2.4 /btrace-bin.zip

      这两天在调试程序时，发现一个比较好用的工具-btrace，能够线上监控程序状态，获取运行时数据信息，如方法返回值，参数，调用次数，全局变量，调用堆栈等。

btrace命令行使用

      位于bin目录下面主要有6个脚本，3个windows的，另外3个是linux的，分别是btrace、btracec、btracer。具体功能如下：

      1、btrace

功能: 用于运行BTrace跟踪程序。
命令格式:
         btrace [-I <include-path>] [-p <port>] [-cp <classpath>] <pid> <btrace-script> [<args>]
示例:
          btrace -cp build/  1200 AllCalls1.java
参数含义:
        include-path指定头文件的路径，用于脚本预处理功能，可选；
        port指定BTrace agent的服务端监听端口号，用来监听clients，默认为2020，可选；
        classpath用来指定类加载路径，默认为当前路径，可选； 
        pid表示进程号，可通过jps命令获取；
        btrace-script即为BTrace脚本；btrace脚本如果以.java结尾，会先编译再提交执行。可使用btracec命令对脚本进行预编译。
       args是BTrace脚本可选参数，在脚本中可通过"$"和"$length"获取参数信息。

     2. btracec

功能: 用于预编译BTrace脚本，用于在编译时期验证脚本正确性。
        btracec [-I <include-path>] [-cp <classpath>] [-d <directory>] <one-or-more-BTrace-.java-files>
参数意义同btrace命令一致，directory表示编译结果输出目录。

3. btracer 

功能: btracer命令同时启动应用程序和BTrace脚本，即在应用程序启动过程中使用BTrace脚本。而btrace命令针对已运行程序执行BTrace脚本。
命令格式:
       btracer <pre-compiled-btrace.class> <application-main-class> <application-args>
参数说明:
       pre-compiled-btrace.class表示经过btracec编译后的BTrace脚本。
       application-main-class表示应用程序代码； 
       application-args表示应用程序参数。 
       该命令的等价写法为: 
              java -javaagent:btrace-agent.jar=script=<pre-compiled-btrace-script1>[,<pre-compiled-btrace-script1>]*        <MainClass> <AppArguments>

btrace脚本限制

In particular, a BTrace class

• can not create new objects.
• can not create new arrays.
• can not throw exceptions.
• can not catch exceptions.
• can not make arbitrary instance or static method calls - only the public static methods of com.sun.btrace.BTraceUtils class may be called from a BTrace program.
• can not assign to static or instance fields of target program's classes and objects. But, BTrace class can assign to it's own static fields ("trace state" can be mutated).
• can not have instance fields and methods. Only static public void returning methods are allowed for a BTrace class. And all fields have to be static.
• can not have outer, inner, nested or local classes.
• can not have synchronized blocks or synchronized methods.
• can not have loops (for, while, do..while)
• can not extend arbitrary class (super class has to be java.lang.Object)
• can not implement interfaces.
• can not contains assert statements.
• can not use class literals.

jvisualvm 插件

BTrace提供了jvisualvm插件，强烈推荐在jvisualvm中编写和测试BTrace脚本，启动、关闭、发送事件、增加classpath都非常方便。

btrace实例

package baby.btrace;

public   class CaseObject{
     
       private static int sleepTotalTime=0; 
       private  int sleepTotalTime2=0; 
     
       public boolean execute(int sleepTime) throws Exception{
           System.out.println("sleep: "+sleepTime);
           sleepTotalTime+=sleepTime;
           sleepTotalTime2=sleepTotalTime+1;
          sleep(sleepTime);
           if(sleepTime%2==0)
               return true;
           else 
               return false;
       }

	 public void sleep(int sleepTime) throws Exception {   
        Thread.sleep(sleepTime);   
    }
     
    }

package baby.btrace;

import java.util.Random;

public class CaseObjectMain {
	int times = 10;

	public static void main(String[] args)  {
		CaseObjectMain main= new CaseObjectMain();
		try {
			main.begin();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public void begin() throws Exception{
		
         CaseObject object=new CaseObject();
         while(true){
        	 times++;
             boolean result=doWork(object);
            Thread.sleep(1000);
         }
	}
	public boolean doWork(CaseObject object) throws Exception{
		 	Random random=new Random();
		
			boolean temp=	object.execute(random.nextInt(1000));
			return  temp;
	}

}

1、获取返回值，参数等信息

/* BTrace Script Template */
import com.sun.btrace.annotations.*;
import static com.sun.btrace.BTraceUtils.*;

@BTrace
public class TracingScript {
    /* put your code here */
/*指明要查看的方法，类*/
  @OnMethod(
     clazz="baby.btrace.CaseObject",
     method="execute",
     location=@Location(Kind.RETURN)
  )
/*主要两个参数是对象自己的引用 和 返回值，其它参数都是方法调用时传入的参数*/
   public static void traceExecute(@Self baby.btrace.CaseObject object,int sleepTime, @Return boolean result){
      println("调用堆栈！！");
       println(strcat("返回结果是：",str(result)));
      jstack();
      println(strcat("时间是：",str(sleepTime)));
   }

}

2、获取对象属性值

/* BTrace Script Template */
import com.sun.btrace.annotations.*;
import static com.sun.btrace.BTraceUtils.*;

@BTrace
public class TracingScript {
    /* put your code here */
/*指明要查看的方法，类*/
  @OnMethod(
     clazz="baby.btrace.CaseObject",
     method="execute",
     location=@Location(Kind.RETURN)
  )
/*主要两个参数是对象自己的引用 和 返回值，其它参数都是方法调用时传入的参数*/
   public static void traceExecute(@Self baby.btrace.CaseObject object,int sleepTime, @Return boolean result){
      println("调用堆栈！！");
       println(strcat("返回结果是：",str(result)));
      jstack();
      println(strcat("时间是：",str(sleepTime)));
   }

}

3、获取方法执行时长

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

@BTrace
public class TracingScript3 {
   @TLS private static long startTime = 0;
   
   @OnMethod(
      clazz="baby.btrace.CaseObject",
      method="execute"
   ) 
   public static void startExecute(){
     startTime = timeNanos();
   } 
    
   @OnMethod(
      clazz="baby.btrace.CaseObject",
      method="execute",
      location=@Location(Kind.RETURN)
   ) 
   public static void endExecute(@Duration long duration){
     long time = timeNanos() - startTime;
     println(strcat("execute time(nanos): ", str(time)));
     println(strcat("duration(nanos): ", str(duration)));
   } 
}

4、正则匹配和获取方法执行次数

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

@BTrace
public class TracingScript4 {
   private static long count; 
     
   @OnMethod(
      clazz="/.*/",
      method="execute",
      location=@Location(value=Kind.CALL, clazz="/.*/", method="sleep")
   )
   public static void traceExecute(@ProbeClassName String pcm, @ProbeMethodName String pmn,
   @TargetInstance Object instance,  @TargetMethodOrField String method){
     println("====== ");
     println(strcat("ProbeClassName: ",pcm));
     println(strcat("ProbeMethodName: ",pmn));
     println(strcat("TargetInstance: ",str(classOf(instance))));
     println(strcat("TargetMethodOrField : ",str(method)));
     count++;
   }
   
   @OnEvent
   public static void getCount(){
       println(strcat("count: ", str(count)));
   }
}

5、正则和事件交互

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

@BTrace
public class TracingScript5 {
   private static long count; 
     
   @OnMethod(
      clazz="/.*/",
      method="execute",
      location=@Location(value=Kind.CALL, clazz="/.*/", method="sleep")
   )
   public static void traceExecute(@ProbeClassName String pcm, @ProbeMethodName String pmn,
   @TargetInstance Object instance,  @TargetMethodOrField String method){
     println("====== ");
     println(strcat("ProbeClassName: ",pcm));
     println(strcat("ProbeMethodName: ",pmn));
     println(strcat("TargetInstance: ",str(classOf(instance))));
     println(strcat("TargetMethodOrField : ",str(method)));
     count++;
   }
   
   @OnEvent
   public static void getCount(){
       println(strcat("count: ", str(count)));
   }
    @OnEvent("A")
   public static void getCountA(){
        println("==AAAA==== ");
       println(strcat("count: ", str(count)));
   }
    @OnEvent("B")
   public static void getCountB(){
        println("==BBB==== ");
       println(strcat("count: ", str(count)));
   }
}

链接：

http://agapple.iteye.com/blog/1005918

http://agapple.iteye.com/blog/962119