Java随笔记 - Java代码实现一个死锁程序

死锁demo

  • 线程死锁是一个经典的多线程问题，因为不同的线程都在等待根本不可能释放的资源，从而导致所有的任务都无法继续完成。这里就不再赘述理论细节，主要是要用代码简单实现一个死锁的程序，具体代码如下：

    // new两个对象用来作为锁
// 两个方法，方法A先获得obj1的锁，睡眠一秒后，尝试去获取obj2的锁
// 方法B先获得obj2的锁，睡眠一秒后，尝试去获取obj1的锁
// 两个方法错开，分别拥有一个锁，再去获取对方手里的锁，就会进入死锁状态

public class DeadLock {

    private Object obj1 = new Object();
    private Object obj2 = new Object();

    public void methodA() {
        synchronized (obj1) {
            System.out.println(Thread.currentThread().getName() + " - get the lock of obj1.");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName() + " - to get the lock of obj2...");
            synchronized (obj2) {
                System.out.println(Thread.currentThread().getName() + " - get the lock of obj2.");
            }
        }
    }

    public void methodB() {
        synchronized (obj2) {
            System.out.println(Thread.currentThread().getName() + " - get the lock of obj2.");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName() + " - to get the lock of obj1...");
            synchronized (obj1) {
                System.out.println(Thread.currentThread().getName() + " - get the lock of obj1.");
            }
        }
    }

}

    public class ServiceA implements Runnable {

    private DeadLock deadLock;

    public ServiceA(DeadLock deadLock) {
        this.deadLock = deadLock;
    }

    @Override
    public void run() {
        deadLock.methodA();
    }
}

public class ServiceB implements Runnable {

    private DeadLock deadLock;

    public ServiceB(DeadLock deadLock) {
        this.deadLock = deadLock;
    }

    @Override
    public void run() {
        deadLock.methodB();
    }
}

public static void main(String[] args) {
        DeadLock deadLock = new DeadLock();
        Thread threadA = new Thread(new ServiceA(deadLock));
        Thread threadB = new Thread(new ServiceB(deadLock));
        threadA.start();
        threadB.start();
}

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Java随笔记 - Java代码实现一个死锁程序