Java并发编程：线程死锁问题案例

原创女爷i 2024-10-15 20:27 53阅读 0赞

线程死锁是多线程编程中常见的问题。简单来说，当两个或更多的线程在执行过程中互相等待对方释放资源时，就会出现死锁。

以下是一个线程死锁的案例：

```java
// 创建两个共享资源
class Resource {
    boolean isUsed = false;

// 为资源添加使用方法
    void use() {
        if (!isUsed) {
            isUsed = true;
            System.out.println("Resource " + this + " used by thread " + Thread.currentThread().getName());
        } else {
            System.out.println("Resource " + this + " already in use by thread " + Thread.currentThread().getName()));
        }
    }

// 为资源添加释放方法
    void release() {
        if (isUsed) {
            isUsed = false;
            System.out.println("Resource " + this + " released by thread " + Thread.currentThread().getName());
        } else {
            System.out.println("Resource " + this + " already not in use when released by thread " + Thread.currentThread().getName()));
        }
    }
}

// 创建两个线程，每个线程都尝试获取资源并使用
class WorkerThread implements Runnable {
    private Resource resource;

public WorkerThread(Resource resource) {
        this.resource = resource;
    }

@Override
    public void run() {
        try {
            System.out.println("Thread " + Thread.currentThread().getName() + " waiting to acquire resource " + resource);

// 线程尝试获取资源
            if (resource.use()) {
                System.out.println("Thread " + Thread.currentThread().getName() + " acquired resource " + resource);
                // 使用资源后，释放资源
                resource.release();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

public class Main {
    public static void main(String[] args) {
        // 创建两个共享资源
        Resource resource1 = new Resource();
        Resource resource2 = new Resource();

// 创建两个线程，每个线程都尝试获取资源并使用
        Thread workerThread1 = new Thread(new WorkerThread(resource1))));
        Thread workerThread2 = new Thread(new WorkerThread(resource2))));

// 启动线程
        workerThread1.start();
        workerThread2.start();
    }
}
```

在这个案例中，两个线程`workerThread1`和`workerThread2`分别尝试获取两个资源`resource1`和`resource2`。如果一个线程成功使用了资源，那么它会释放资源给其他的线程。这就可能导致死锁，因为每个线程都在等待对方释放资源。