Java Multi-Threading Gone اشتباه: یک کابوس پس زمینه واقعی در دنیای واقعی

class Resource {
    private final String name;
    public Resource(String name) { this.name = name; }
    public String getName() { return name; }
}

class DeadlockExample {
    private final Resource resource1 = new Resource("Database Connection");
    private final Resource resource2 = new Resource("Cache Layer");

    public void processA() {
        synchronized (resource1) {
            System.out.println(Thread.currentThread().getName() + " locked " + resource1.getName());
            try { Thread.sleep(100); } catch (InterruptedException ignored) {}
            synchronized (resource2) {
                System.out.println(Thread.currentThread().getName() + " locked " + resource2.getName());
            }
        }
    }

    public void processB() {
        synchronized (resource2) {
            System.out.println(Thread.currentThread().getName() + " locked " + resource2.getName());
            try { Thread.sleep(100); } catch (InterruptedException ignored) {}
            synchronized (resource1) {
                System.out.println(Thread.currentThread().getName() + " locked " + resource1.getName());
            }
        }
    }
}

public class DeadlockSimulator {
    public static void main(String[] args) {
        DeadlockExample system = new DeadlockExample();
        Thread t1 = new Thread(system::processA, "Thread-A");
        Thread t2 = new Thread(system::processB, "Thread-B");
        t1.start();
        t2.start();
    }
}

public void safeProcess() {
    synchronized (resource1) {  // Always lock DB first
        System.out.println(Thread.currentThread().getName() + " locked " + resource1.getName());
        try { Thread.sleep(100); } catch (InterruptedException ignored) {}
        synchronized (resource2) {  // Then lock Cache
            System.out.println(Thread.currentThread().getName() + " locked " + resource2.getName());
        }
    }
}

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

class SafeResource {
    private final Lock lock = new ReentrantLock();

    public boolean tryLock() {
        return lock.tryLock();
    }

    public void unlock() {
        lock.unlock();
    }
}