java多线程笔记--lock多线程计数

Posted 2022-12-03 SingleOneMan

java多线程笔记–lock多线程计数

文章目录

• java多线程笔记--lock多线程计数
• • • 1.lock多线程计数

lock：主要有可重入锁，读写锁，文件锁

1.lock多线程计数

package com.ctg.test.lock;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.locks.ReentrantLock;

/**
 * @Description: Lock解决多线程访问相同的资源
 * lock的特性：
 * 1）相比于 synchronized隐式获取、释放锁，lock需要显示的获取释放锁
 * 2）相比于 synchronized，lock可以可中断的获取锁及超时获取锁，
 * 3）ReentrantLock，同一个线程调用lock方法，可以连续多次获取锁而不被阻塞
 * @Author: 
 * @Date: 2019/5/12 0:05
 */
public class TestLockCount 
    private  static  int num =0;
    private  static ReentrantLock lock = new ReentrantLock();
    public static void main(String[] args)throws InterruptedException 
        for(int k=0;k<100;k++)
            CountDownLatch countDownLatch = new CountDownLatch(3);
            num=0;
            Thread t1 =new Thread(new CountRunnable(countDownLatch));
            Thread t2 =new Thread(new CountRunnable(countDownLatch));
            Thread t3 =new Thread(new CountRunnable(countDownLatch));
            t1.start();
            t2.start();
            t3.start();
            countDownLatch.await();
            System.out.println("第"+(k+1)+"次计算结果，num=" + num);
        
    

    public static  class CountRunnable implements Runnable
        private CountDownLatch countDownLatch;
        CountRunnable (CountDownLatch countDownLatch)
            this.countDownLatch=countDownLatch;
        
        @Override
        public void run() 
            lock.lock();
            try
                for (int i=0;i<10000;i++)
                    num=num+1;
                    // System.out.println(Thread.currentThread().getName()+":"+num);
                
            
            finally 
                lock.unlock();
            
            countDownLatch.countDown();
        
    

执行100次结果：