Two customers add a product to the basket in the same t...

Addressing the scenario where two customers attempt to add the same product to their baskets simultaneously when only one item is in stock involves careful consideration of inventory management and user experience. The solution to this problem can be approached from both a technical and a business perspective. Here's a detailed explanation:

Technical Perspective

1. Optimistic Locking: This approach involves allowing both customers to add the item to their baskets without immediately checking stock levels. When the first customer proceeds to checkout and the payment is processed, the inventory is then decremented. If the second customer attempts to checkout afterwards, the system checks the inventory again and, finding the item out of stock, informs the customer that the item is no longer available. This method minimizes locking in the database but requires a good user interface strategy to manage customer expectations.

2. Pessimistic Locking: When a customer adds an item to their basket, the system immediately locks the inventory for a short period. If the customer proceeds to checkout and completes the purchase within this period, the stock is decremented, and the sale goes through. If another customer attempts to add the same last item to their basket while it's locked, they are informed that the item is currently being purchased by another customer and can choose to be notified if the item becomes available again. This approach requires managing lock timeouts effectively to avoid deadlocks or long waiting times for other customers.

3. Real-Time Inventory Updates: Implement a system where inventory levels are updated in real-time and displayed to customers. When the stock level of an item is one, and a customer adds it to their basket, the inventory immediately updates to reflect that the item is no longer available. This requires a robust back-end system capable of handling real-time data efficiently and ensuring accurate inventory levels are always displayed to customers.

4. Queue System: In high-demand scenarios, implement a queue system where customers express interest in a product and are queued for purchase. When the product is added to a basket, the first customer in the queue has a limited time to complete the purchase before it's offered to the next customer in line. This system must be transparent to customers to ensure they understand the process and estimated wait times.

Business Perspective

1. Backorder or Pre-order Options: If the product can be restocked quickly, allow customers to backorder or pre-order the item. This way, even if the product is out of stock at the moment of purchase, customers are assured they will receive it once it's available again.

2. Alternative Recommendations: If a product is out of s...