lock、tryLock和lockInterruptibly的差別

lock():若lock被thread A取得,thread B会进入block状态,直到取得lock;
tryLock():若当下不能取得lock,thread就会放弃,可以设置一个超时时间参数,等待多久获取不到锁就放弃;
lockInterruptibly():跟lock()情況一下,但是thread B可以通过interrupt中断,放弃继续等待锁

 

lock 与 lockInterruptibly比较区别在于:lock 优先考虑获取锁,待获取锁成功后,才响应中断,而lockInterruptibly 优先考虑响应中断 

ReentrantLock.lockInterruptibly允许在等待时由其它线程调用等待线程的Thread.interrupt方法来中断等待线程的等待而直接返回,这时不用获取锁,而会抛出一个InterruptedException

ReentrantLock.lock方法不允许Thread.interrupt中断,即使检测到Thread.isInterrupted,一样会继续尝试获取锁,失败则继续休眠。只是在最后获取锁成功后再把当前线程置为interrupted状态,然后再中断线程

public class LockDemo {

    private ReentrantLock lock = new ReentrantLock();

    public static void main(String[] args) throws InterruptedException {
        final LockDemo lockDemo = new LockDemo();

        Thread threada = new Thread("Thread A") {
            @Override
            public void run() {
                lockDemo.doSomeThing3(Thread.currentThread());
            }
        };
        threada.start();

        Thread threadb = new Thread("Thread B") {
            @Override
            public void run() {
                lockDemo.doSomeThing3(Thread.currentThread());
            }
        };
        threadb.start();
        
        //threadb.interrupt();
    }

    public void doSomeThing1(Thread thread) {
        lock.lock();
        try {
            System.out.println(thread.getName() + "得到了锁.");
            Thread.sleep(1000);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            System.out.println(thread.getName() + "释放了锁.");
            lock.unlock();
        }
    }
    
    
    public void doSomeThing2(Thread thread) {
        if (lock.tryLock()) {
            try {
                System.out.println(thread.getName() + "得到了锁.");
                Thread.sleep(1000);
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                System.out.println(thread.getName() + "释放了锁.");
                lock.unlock();
            }
        } else {
            System.out.println(thread.getName() + "获取锁失败.");
        }
    }

    public void doSomeThing3(Thread thread) {
        try {
            lock.lockInterruptibly();
            System.out.println(thread.getName() + " 得到了锁.");
            Thread.sleep(6000);
        } catch (InterruptedException e1) {
            e1.printStackTrace();
            System.out.println(thread.getName() + " interrupted.");
        } finally {
            System.out.println(thread.getName() + " 释放了锁.");
            lock.unlock();
        }
    }

}

 

 

posted @ 2019-10-23 15:23  踏月而来  阅读(1082)  评论(0编辑  收藏  举报