JAVA并发编程6

Posted 2020-11-01 Gggoblin

说明：先上代码，笔记后续补充。
public class LockTest2 {
    private ReentrantReadWriteLock lock = new ReentrantReadWriteLock();

    public static void main(String[] args) {
        final CountDownLatch latch = new CountDownLatch(2);
        Long startTime = System.currentTimeMillis();
        final LockTest2 test = new LockTest2();

        Thread thread1 = new Thread(new Runnable() {
            @Override
            public void run() {
                test.superGet(Thread.currentThread());
                latch.countDown();
            }
        },"thread1");

        Thread thread2 = new Thread(new Runnable() {
            @Override
            public void run() {
                test.superGet(Thread.currentThread());
                latch.countDown();
            }
        },"thread2");

        thread1.start();
        thread2.start();
        try {
            latch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        long endTime = System.currentTimeMillis();
        long result = endTime - startTime;
        System.out.println("共耗时"+result);
    }

    //改良之后的get
    private void superGet(Thread thread){
        try {
            lock.readLock().lock();
            //lock.writeLock().lock();   这个≈synchronized
            long start = System.currentTimeMillis();
            while (System.currentTimeMillis() - start <= 1){
                System.out.println(thread.getName()+"正在执行读操作");
            }
            System.out.println(thread.getName()+"读操作完毕");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
          lock.readLock().unlock();
        }
    }

    private synchronized void get(Thread thread){
        long start = System.currentTimeMillis();
        while (System.currentTimeMillis() - start <= 1){
            System.out.println(thread.getName()+"正在执行读操作");
        }
        System.out.println(thread.getName()+"读操作完毕");
    }
}