Spring中JDK动态代理和CGLIB动态代理的性能_JAVA_编程开发_程序员俱乐部

    新项目开始之前领导让研究下公司原有的框架(基于struts1.2.9+spring2.0.6)，比较古老了。读service基类时发现竟然将request穿透到了service层(request为BaseService的实例变量)，这样service就变成了有状态Bean，使service层变成了非线程安全，导致用Spring容器管理service的时候不得不使用prototype的scope
    我们知道，service由于要做事务的包装，需要创建代理对象，spring中使用JDK动态代理或者CGLIB动态代理来创建代理对象，据说JDK动态代理创建对象的时间快于CGLIB，但是性能比CGLIB差（接下来我会测试这个观点），所以我得出以下结论：
1.spring在bean的scope为prototype的情况下，因为是延迟实例化bean，所以最好使用JDK的API创建代理对象；
2.反之对于singleton对象，spring默认是容器启动时就初始化bean，最好使用CGLIB来创建对象

把service配置成singleton我觉得性能方面显然要更好些，如果非要将request穿透到service层，是不是可以考虑用ThreadLocal？

在测试之前，我们先确定spring是以什么方式使用JDK动态代理和CGLIB的，如图：
JDK动态代理：



CGLIB动态代理：


接下来对测试下JDK动态代理和CGLIB动态代理的性能（CGLIB测试代码也和spring一样使用MethodInterceptor）

先贴上测试代码

public interface CountService {
    int count();
}

public class CountServiceImpl implements CountService {
    private int count = 0;
    
    public int count() {
        return ++count;
    }
}

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.text.DecimalFormat;

import net.sf.cglib.core.DefaultGeneratorStrategy;
import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

@SuppressWarnings("unused")
public class DynamicProxyPerformanceTest {
    
    public static void main(String[] args) throws Exception {
        CountService delegate = new CountServiceImpl();
        
        long time = System.currentTimeMillis();
        CountService jdkProxy = createJdkDynamicProxy(delegate);
        time = System.currentTimeMillis() - time;
        System.out.println("Create JDK Proxy: " + time + " ms");
        
        time = System.currentTimeMillis();
        CountService cglibProxy = createCglibDynamicProxy(delegate);
        time = System.currentTimeMillis() - time;
        System.out.println("Create CGLIB Proxy: " + time + " ms");
        
        for (int i = 0; i < 3; i++) {
            test(jdkProxy, "Run JDK Proxy: ");
            test(cglibProxy, "Run CGLIB Proxy: ");
            System.out.println("-------------------");
        }
    }
    
    private static void test(CountService service, String label) throws Exception {
        service.count(); // warm up
        int count = 10000000;
        long time = System.currentTimeMillis();
        for (int i = 0; i < count; i++) {
            service.count();
        }
        time = System.currentTimeMillis() - time;
        System.out.println(label + time + " ms, " + new DecimalFormat().format(count * 1000 / time) + " t/s");
    }
    
    private static CountService createJdkDynamicProxy(final CountService delegate) {
        CountService jdkProxy = (CountService) Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(),
                new Class[] { CountService.class }, new JdkHandler(delegate));
        
        // 反汇编字节码用，测试的时候注释掉这段代码，不然影响测试结果
        // 下面一行代码参照java.lang.reflect.Proxy
//        byte[] proxyClassFile =
//                sun.misc.ProxyGenerator.generateProxyClass(
//                        jdkProxy.getClass().getName(), jdkProxy.getClass().getInterfaces());
//        try {
//            FileOutputStream fos =
//                    new FileOutputStream(new File(jdkProxy.getClass().getName() + ".class"));
//            fos.write(proxyClassFile, 0, proxyClassFile.length);
//        } catch (FileNotFoundException e) {
//            e.printStackTrace();
//        } catch (IOException e) {
//            e.printStackTrace();
//        }
        return jdkProxy;
    }
    
    private static class JdkHandler implements InvocationHandler {
        
        final Object delegate;
        
        JdkHandler(Object delegate) {
            this.delegate = delegate;
        }
        
        public Object invoke(Object object, Method method, Object[] objects) throws Throwable {
            return method.invoke(delegate, objects);
        }
    }
    
    private static CountService createCglibDynamicProxy(final CountService delegate) throws Exception {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(CountServiceImpl.class);
        enhancer.setCallback(new MethodInterceptor() {
            @Override
            public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
                return proxy.invokeSuper(obj, args);
            }
        });
        CountServiceImpl cglibProxy = (CountServiceImpl) enhancer.create();
        // 反汇编字节码用，测试的时候注释掉这段代码，不然影响测试结果
        // 下面一行代码参照net.sf.cglib.core.AbstractClassGenerator类中byte[] b = strategy.generate(this);
//        byte[] proxyClassFile = new DefaultGeneratorStrategy().generate(enhancer);
//        try {
//            FileOutputStream fos =
//                    new FileOutputStream(new File(cglibProxy.getClass().getName() + ".class"));
//            fos.write(proxyClassFile, 0, proxyClassFile.length);
//        } catch (FileNotFoundException e) {
//            e.printStackTrace();
//        } catch (IOException e) {
//            e.printStackTrace();
//        }
        return cglibProxy;
    }
}

数据为执行三次，每次调用一千万次代理方法的结果
测试环境1：
JDK：fastdebug1.6
CGLIB：和spring2.0.6 使用同样的cglib-nodep-2.1_3.jar
CPU：P8400 2.53GHz 2.53GHz
测试结果1：

Create JDK Proxy: 13 ms
Create CGLIB Proxy: 201 ms
Run JDK Proxy: 1571 ms, 897,559 t/s
Run CGLIB Proxy: 824 ms, 1,711,244 t/s
-------------------
Run JDK Proxy: 1519 ms, 928,285 t/s
Run CGLIB Proxy: 576 ms, 2,448,030 t/s
-------------------
Run JDK Proxy: 1546 ms, 912,073 t/s
Run CGLIB Proxy: 590 ms, 2,389,941 t/s
-------------------

CGLIB创建代理对象速度大概比JDK Proxy慢15倍，执行速度是JDK Proxy的2倍左右

测试环境2：
JDK：fastdebug1.7
CGLIB：和spring2.0.6 使用同样的cglib-nodep-2.1_3.jar
CPU：P8400 2.53GHz 2.53GHz
测试结果2：

Create JDK Proxy: 14 ms
Create CGLIB Proxy: 204 ms
Run JDK Proxy: 1608 ms, 876,906 t/s
Run CGLIB Proxy: 529 ms, 2,665,530 t/s
-------------------
Run JDK Proxy: 1591 ms, 886,276 t/s
Run CGLIB Proxy: 405 ms, 3,481,642 t/s
-------------------
Run JDK Proxy: 1624 ms, 868,266 t/s
Run CGLIB Proxy: 405 ms, 3,481,642 t/s
-------------------

CGLIB创建代理对象速度大概比JDK Proxy慢15倍，执行速度是JDK Proxy的4倍左右

测试环境3：
JDK：jdk1.6.0_21
CGLIB：和spring2.0.6 使用同样的cglib-nodep-2.1_3.jar
CPU：P8400 2.53GHz 2.53GHz
测试结果3：

Create JDK Proxy: 8 ms
Create CGLIB Proxy: 99 ms
Run JDK Proxy: 911 ms, 1,547,821 t/s
Run CGLIB Proxy: 435 ms, 3,241,529 t/s
-------------------
Run JDK Proxy: 870 ms, 1,620,764 t/s
Run CGLIB Proxy: 399 ms, 3,533,998 t/s
-------------------
Run JDK Proxy: 894 ms, 1,577,254 t/s
Run CGLIB Proxy: 404 ms, 3,490,260 t/s
-------------------

CGLIB创建代理对象速度大概比JDK Proxy慢10倍以上，执行速度是JDK Proxy的2倍左右

测试环境4：
JDK：jdk1.7.0_02
CGLIB：和spring2.0.6 使用同样的cglib-nodep-2.1_3.jar
CPU：P8400 2.53GHz 2.53GHz
测试结果4：

Create JDK Proxy: 43 ms
Create CGLIB Proxy: 129 ms
Run JDK Proxy: 940 ms, 1,500,069 t/s
Run CGLIB Proxy: 299 ms, 4,715,937 t/s
-------------------
Run JDK Proxy: 921 ms, 1,531,015 t/s
Run CGLIB Proxy: 269 ms, 5,241,878 t/s
-------------------
Run JDK Proxy: 932 ms, 1,512,945 t/s
Run CGLIB Proxy: 265 ms, 5,321,001 t/s
-------------------

CGLIB创建代理对象速度大概比JDK Proxy慢3倍，执行速度是JDK Proxy的3倍以上

字节码比较：
把测试代码中被注释的部分打开，生成class文件后执行javap -c 类名
JDK动态代理生成的字节码：

  public final int count() throws ;
    Code:
       0: aload_0       
       1: getfield      #16                 // Field java/lang/reflect/Proxy.h:Ljava/lang/reflect/InvocationHandler;
       4: aload_0       
       5: getstatic     #50                 // Field m3:Ljava/lang/reflect/Method;
       8: aconst_null   
       9: invokeinterface #28,  4           // InterfaceMethod java/lang/reflect/InvocationHandler.invoke:(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;
      14: checkcast     #52                 // class java/lang/Integer
      17: invokevirtual #55                 // Method java/lang/Integer.intValue:()I
      20: ireturn       
      21: athrow        
      22: astore_1      
      23: new           #42                 // class java/lang/reflect/UndeclaredThrowableException
      26: dup           
      27: aload_1       
      28: invokespecial #45                 // Method java/lang/reflect/UndeclaredThrowableException."<init>":(Ljava/lang/Throwable;)V
      31: athrow        
    Exception table:
       from    to  target type
           0    21    21   Class java/lang/Error
           0    21    21   Class java/lang/RuntimeException
           0    21    22   Class java/lang/Throwable

CGLIB生成的字节码：

  public final int count();
    Code:
       0: aload_0       
       1: getfield      #37                 // Field CGLIB$CALLBACK_0:Lnet/sf/cglib/proxy/MethodInterceptor;
       4: dup           
       5: ifnonnull     17
       8: pop           
       9: aload_0       
      10: invokestatic  #41                 // Method CGLIB$BIND_CALLBACKS:(Ljava/lang/Object;)V
      13: aload_0       
      14: getfield      #37                 // Field CGLIB$CALLBACK_0:Lnet/sf/cglib/proxy/MethodInterceptor;
      17: dup           
      18: ifnull        52
      21: aload_0       
      22: getstatic     #43                 // Field CGLIB$count$0$Method:Ljava/lang/reflect/Method;
      25: getstatic     #45                 // Field CGLIB$emptyArgs:[Ljava/lang/Object;
      28: getstatic     #47                 // Field CGLIB$count$0$Proxy:Lnet/sf/cglib/proxy/MethodProxy;
      31: invokeinterface #53,  5           // InterfaceMethod net/sf/cglib/proxy/MethodInterceptor.intercept:(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;Lnet/sf/cglib/proxy/MethodProxy;)Ljava/lang/Object;
      36: dup           
      37: ifnonnull     45
      40: pop           
      41: iconst_0      
      42: goto          51
      45: checkcast     #55                 // class java/lang/Number
      48: invokevirtual #58                 // Method java/lang/Number.intValue:()I
      51: ireturn       
      52: aload_0       
      53: invokespecial #35                 // Method CountServiceImpl.count:()I
      56: ireturn       

疑问：性能的差距是不是差在JDK动态代理的对异常的处理上？

本文参照了 http://javatar.iteye.com/blog/814426

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