21. Short Q&A Prompts

Rapid prompts to demonstrate depth and judgment on the spot.

• Contrast __getattr__ vs __getattribute__; show a safe pattern to avoid recursion.
• Explain the descriptor protocol and implement a validated field.
• Metaclass practical use: registration or auto-validation.
• Backpressure in asyncio: semaphores vs bounded queues; when to use each?
• Prevent cache stampede: locks, TTL jitter, refresh-ahead, single-flight.
• Exactly-once vs effectively-once; design idempotent consumers.
• Transaction isolation levels: choose one for a given scenario and justify.
• Transactional Outbox: why it solves dual-write problems.
• Observability: when to add tracing spans vs structured logs.
• JWT pitfalls and key rotation strategy.