多线程死锁

死锁出现的原因：线程A和线程B相互等待对方持有的锁导致程序无限死循环下去。

死锁代码：

 

private static Object lock1 = new Object();
private static Object lock2 = new Object();

public static void main(String[] args) {
    new Thread() {

        public void run() {
            synchronized (lock1) {
                System.out.println("Thread1 get lock1");
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                synchronized (lock2) {
                    System.out.println("Thread1 get lock2");
                }
            }
            System.out.println("Thread1 end");
        }
    }.start();

    new Thread() {

        public void run() {
            synchronized (lock2) {
                System.out.println("Thread2 get lock2");
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                synchronized (lock1) {
                    System.out.println("Thread2 get lock1");
                }
            }
            System.out.println("Thread2 end");
        }
    }.start();
}

输出结果：

Thread1 get lock1
Thread2 get lock2

 

两个线程相互得到锁1，锁2，然后线程1等待线程2释放锁2，线程2等待线程1释放锁1，两者各不相互，这样形成死锁。