Java多线程同步问题：死锁案例分析

原创布满荆棘的人生 2024-11-27 07:15 31阅读 0赞

死锁是多线程编程中的一种严重问题。当两个或更多的线程在执行过程中，因争夺资源而造成的一种互相等待的现象称为死锁。

以下是一个简单的Java死锁案例：

```java
// 线程1
class Thread1 extends Thread {
    private Object lock1 = new Object();
    private Object lock2 = new Object();

public void run() {
        synchronized(lock1) {
            System.out.println("Thread 1: Acquire lock 1");
            try {
                // 等待锁2，模拟资源争夺
                synchronized(lock2) {
                    System.out.println("Thread 1: Wait for lock 2");
                }
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                System.out.println("Thread 1: Interrupted while waiting for lock 2");
            }

System.out.println("Thread 1: Release lock 1");
        }

// 等待锁1释放，模拟资源争夺
        synchronized(lock1) {
            System.out.println("Thread 1: Wait for lock 1 to release");
        }
    }
}

// 线程2
class Thread2 extends Thread {
    private Object lock1 = new Object();
    private Object lock2 = new Object();

public void run() {
        synchronized(lock1) {
            System.out.println("Thread 2: Acquire lock 1");
            try {
                // 等待锁2释放，模拟资源争夺
                synchronized(lock2) {
                    System.out.println("Thread 2: Wait for lock 2 to release");
                }
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                System.out.println("Thread 2: Interrupted while waiting for lock 2 to release");
            }

System.out.println("Thread 2: Release lock 1");
        }

// 等待锁1释放，模拟资源争夺
        synchronized(lock1) {
            System.out.println("Thread 2: Wait for lock 1 to release");
        }
    }
}

public class Main {
    public static void main(String[] args) {
        Thread1 thread1 = new Thread1();
        Thread2 thread2 = new Thread2();

thread1.start();
        thread2.start();
    }
}
```

在这个案例中，线程1首先获取到锁1，然后等待锁2释放。与此同时，线程2也是先获取锁1，然后等待锁1释放。

如果线程2在等待锁1释放期间被中断（例如，操作系统认为线程不应该继续运行），那么线程2将无法获取到锁1，从而导致死锁。