ReentrantReadWriteLock实现原理

前言

读读共享

public static void main(String[] args) {

    ReentrantReadWriteLock lock = new ReentrantReadWriteLock();

    /*
     * 1525541261947 Thread-0 获得读锁
     * 1525541261947 Thread-2 获得读锁
     * 1525541261947 Thread-1 获得读锁
     */

    for (int i = 0; i < 3; i++) {
        new Thread(() -> {
            lock.readLock().lock();
            try {
                System.out.println(System.currentTimeMillis() + " " + Thread.currentThread().getName() + " 获得读锁");
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                lock.readLock().unlock();
            }
        }).start();
    }
}

写写互斥

public static void main(String[] args) {

    ReentrantReadWriteLock lock = new ReentrantReadWriteLock();

    /*
     * 1525541686021 Thread-0 获得写锁
     * 1525541687023 Thread-2 获得写锁
     * 1525541688023 Thread-1 获得写锁
     */

    for (int i = 0; i < 3; i++) {
        new Thread(() -> {
            lock.writeLock().lock();
            try {
                System.out.println(System.currentTimeMillis() + " " + Thread.currentThread().getName() + " 获得写锁");
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                lock.writeLock().unlock();
            }
        }).start();
    }
}

读写互斥

public static void main(String[] args) {

    ReentrantReadWriteLock lock = new ReentrantReadWriteLock();

    /*
     * 1525541885280 Thread-0 获得写锁
     * 1525541886282 Thread-1 获得读锁
     */

    new Thread(() -> {
        lock.writeLock().lock();
        try {
            System.out.println(System.currentTimeMillis() + " " + Thread.currentThread().getName() + " 获得写锁");
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.writeLock().unlock();
        }
    }).start();

    new Thread(() -> {
        lock.readLock().lock();
        try {
            System.out.println(System.currentTimeMillis() + " " + Thread.currentThread().getName() + " 获得读锁");
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.readLock().unlock();
        }
    }).start();
}

参考博客