同步块内的线程抛出异常锁是否还在

public class Test {
    public static void main(String[] args) throws InterruptedException {
        final Object o = new Object();
        Runnable r1 = new Runnable() {
            public void run() {
                synchronized (o) {
                    throw new RuntimeException("throws");
                }
            }
        };
        Runnable r2 = new Runnable() {
            public void run() {
                synchronized(o) {
                    System.out.println("acquire lock");
                }
            }
        };
        
        new Thread(r1).start();
        Thread.sleep(1000);
        new Thread(r2).start();
            
    }

}

运行结果：

Exception in thread "Thread-0" java.lang.RuntimeException: throws
    at Test$1.run(Test.java:11)
    at java.lang.Thread.run(Thread.java:748)
acquire lock

如果是lock 就不能这样：下面是错误的示例

public class Test {
    public static void main(String[] args) throws InterruptedException {
        final Object o = new Object();
        final Lock lock =new Lock();
        Runnable r1 = new Runnable() {
            public void run() {
                try {
                    lock.lock();
                    if(true)
                        throw new RuntimeException("throws");
                    lock.unlock();
                }catch (Exception e){

                }
            }
        };
        Runnable r2 = new Runnable() {
            public void run() {
                synchronized(o) {
                    try {
                        System.out.println("开始");
                        lock.lock();
                    System.out.println("acquire lock");
                        lock.unlock();
                }catch (Exception e){

                }
                }
            }
        };

        new Thread(r1).start();
        Thread.sleep(1000);
        new Thread(r2).start();

    }

}

正确的示例：所以一定要记得在finally 中释放锁。

public class Test {
    public static void main(String[] args) throws InterruptedException {
        final Object o = new Object();
        final Lock lock =new Lock();
        Runnable r1 = new Runnable() {
            public void run() {
                try {
                    lock.lock();
                    if(true)
                        throw new RuntimeException("throws");

                }catch (Exception e){

                }finally {
                    lock.unlock();
                }
            }
        };
        Runnable r2 = new Runnable() {
            public void run() {
                synchronized(o) {
                    try {
                        System.out.println("开始");
                        lock.lock();
                        System.out.println("acquire lock");
                    }catch (Exception e){

                    }finally {
                        lock.unlock();
                    }
                }
            }
        };

        new Thread(r1).start();
        Thread.sleep(1000);
        new Thread(r2).start();

    }

}