Java并发编程中的死锁问题示例

原创绝地灬酷狼 2024-09-16 22:57 73阅读 0赞

在Java并发编程中，死锁通常发生在两个或更多的线程相互等待对方释放资源的情况下。

以下是一个简单的死锁示例：

```java
// 定义资源
class Resource {
    int value;
    boolean locked;

Resource(int value) {
        this.value = value;
        this.locked = false;
    }
}

// 线程类
class ThreadA extends Thread {
    private Resource resourceA, resourceB;

ThreadA(Resource resourceA, Resource resourceB) {
        this.resourceA = resourceA;
        this.resourceB = resourceB;
    }

@Override
    public void run() {
        synchronized (resourceA) {
            if (!resourceA.locked) {
                System.out.println("Thread A acquiring resource A.");
                resourceA.locked = true;

// 确保资源B未被其他线程锁定
                if (!resourceB.locked && !resourceA.value % 2) {
                    System.out.println("Thread A acquiring resource B.");
                    resourceB.locked = true;
                }
            } else {
                System.out.println("Resource A is already locked by Thread A.");
            }
        }

synchronized (resourceB) {
            if (!resourceB.locked && !resourceA.value % 2) {
                System.out.println("Thread A releasing resource B.");
                resourceB.locked = false;
            } else if (!resourceB.locked) {
                System.out.println("Resource B is already locked by another thread.");
            }
        }

System.out.println("Thread A completed its cycle.");
    }
}

public class Main {
    public static void main(String[] args) {
        Resource resourceA = new Resource(1);
        Resource resourceB = new Resource(2);

ThreadA threadA = new ThreadA(resourceA, resourceB));
        threadA.start();
    }
}
```

在这个示例中，两个线程`ThreadA`和`ThreadB`分别尝试获取资源A和资源B。如果一个线程已经持有某个资源并等待其他资源，而另一个线程同时请求这两项资源，就会发生死锁。