Java多线程编程：共享资源导致的死锁问题案例

原创ゞ浴缸里的玫瑰 2024-12-08 15:03 38阅读 0赞

在Java多线程编程中，死锁是一个常见的并发问题。当两个或更多的线程互相等待对方释放资源时，就会形成死锁。

以下是一个死锁案例：

```java
// 定义两个共享资源类
class ResourceA {
    private int count = 10;

public synchronized void acquire() {
        if (count > 0) {
            count--;
            notifyAll(); // 等待的线程收到通知后进入循环
        } else {
            throw new IllegalStateException("Resource A is out of stock.");
        }
    }

public synchronized void release() {
        count++;
        notifyAll(); // 同步唤醒等待的线程
    }
}

class ResourceB {
    private int count = 5;

public synchronized void acquire() {
        if (count > 0) {
            count--;
            notifyAll();
        } else {
            throw new IllegalStateException("Resource B is out of stock.");
        }
    }

public synchronized void release() {
        count++;
        notifyAll();
    }
}

// 创建两个线程，分别尝试获取资源A和资源B
public class DeadlockExample {
    public static void main(String[] args) {
        ResourceA resourceA = new ResourceA();
        ResourceB resourceB = new ResourceB();

Thread thread1 = new Thread(() -> {
            while (!resourceA.acquire()) {
                // 线程在此处等待资源
            }
            System.out.println("Thread 1 acquired Resource A and is acquiring Resource B.");
            try {
                resourceB.acquire();
                // 线程在此处尝试获取资源B，可能会因为资源A的限制而失败
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("Thread 1 released both resources.");
        }));

Thread thread2 = new Thread(() -> {
            while (!resourceB.acquire()) {
                // 线程在此处等待资源
            }
            System.out.println("Thread 2 acquired Resource B and is acquiring Resource A.");
            try {
                resourceA.acquire();
                // 线程在此处尝试获取资源A，可能会因为资源B的限制而失败
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("Thread 2 released both resources.");
        }));

thread1.start();
        thread2.start();

// 程序运行结束后，确保所有线程正常结束
    }
}
```

这个例子展示了两个资源类（ResourceA和ResourceB）以及两个尝试获取这些资源的线程。由于资源有限，线程之间的交互可能会导致死锁。