通过CountDownLatch模拟高并发下测试各种单例模式的执行结果

亦凉 2022-05-30 05:59 195阅读 0赞

单例模式一般写法有多种，那么哪种相对来说效果比较好。下面一起看看我的测试结果吧。

我是通过CountDownLatch来模拟刚并发下，各种单例模式的执行结果。自己做加深影响所写，所以写的比较粗糙，希望大家不要介意。

先上代码吧，后面做结果说明

1、最基础的单例

package singleton;
    
    /**
     * 最简单的单例
     */
    public class MySingleton {
    
        private static   MySingleton mySingleton = null;
    
        public static MySingleton getInstance(){
            if(mySingleton == null){
                System.out.println(System.currentTimeMillis());
                 mySingleton = new MySingleton();
            }
            return mySingleton;
        }
    }

2、带锁的单例

package singleton;
    
    /**
     * 最简单的单例
     */
    public class MySingleton2 {
    
        private static MySingleton2 mySingleton = null;
    
        private static Object obj = new Object();
    
        public static MySingleton2 getInstance(){
            if(mySingleton == null){
                System.out.println(System.currentTimeMillis());
                synchronized (obj){
                    if(mySingleton == null){
                        mySingleton = new MySingleton2();
                    }
                }
    
            }
            return mySingleton;
        }
    }

3、测试最简单的单例类

package singleton;
    
    import java.util.concurrent.CountDownLatch;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    
    /**
     * 测试类
     */
    public class Test {
        /**
         * 模拟client_num个客户端同时访问
         */
        private static int clientNum = 1000;
        private static int threadsNum = 10;
        /**
         * 计数器
         */
        final static CountDownLatch doneSignal = new CountDownLatch(clientNum);
        public static void main(String[] args) {
            /**
             * 建立线程池
             */
            ExecutorService exec = Executors.newFixedThreadPool(threadsNum);
            for(int i=0 ; i< clientNum; i++){
                 MyRunnable myRunnable = new MyRunnable();
                 exec.execute(myRunnable);
                 doneSignal.countDown();
             }
        }
    
         static class  MyRunnable implements  Runnable{
            @Override
            public void run() {
                try{
                    doneSignal.await();
                }catch (Exception e){
                    e.printStackTrace();
                }
                System.out.println(MySingleton.getInstance()+"=");
            }
        }
    
    }

测试结果：

![70][]

4、上锁的单例测试类

package singleton;
    
    import java.util.concurrent.CountDownLatch;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    
    /**
     * 测试类
     */
    public class Test {
        /**
         * 模拟client_num个客户端同时访问
         */
        private static int clientNum = 100;
        private static int threadsNum = 5;
        /**
         * 计数器
         */
        final static CountDownLatch doneSignal = new CountDownLatch(clientNum);
        public static void main(String[] args) {
            /**
             * 建立线程池
             */
            ExecutorService exec = Executors.newFixedThreadPool(threadsNum);
            for(int i=0 ; i< clientNum; i++){
                 MyRunnable myRunnable = new MyRunnable();
                 exec.execute(myRunnable);
                 doneSignal.countDown();
             }
        }
    
         static class  MyRunnable implements  Runnable{
            @Override
            public void run() {
                try{
                    doneSignal.await();
                }catch (Exception e){
                    e.printStackTrace();
                }
                System.out.println(MySingleton2.getInstance()+"=");
            }
        }
    
    }

测试结果：

![70 1][]

[70]: /images/20220530/c8338be7bb214d19959a4cf5aa999c84.png
[70 1]: /images/20220530/765be5244de14704807e29e494807af8.png