Graceful Degradation
When systems fail, they shouldn’t fail completely.
Graceful degradation means continuing to provide partial service rather than a full outage.
1. Why Graceful Degradation?
- Improves user experience during failures.
- Maintains business continuity (some features still usable).
- Builds resilience into large-scale systems.
2. Examples of Graceful Degradation
E-commerce
- Checkout service down → users can still browse products.
- Payment fallback (retry later, or alternate gateway).
Streaming (Netflix, YouTube)
- HD unavailable → fallback to SD video.
- Continue serving cached recommendations if backend is slow.
Social Media
- Feed service down → still allow posting or messaging.
- Show cached timeline if live updates unavailable.
Maps & Navigation
- Live traffic unavailable → still show static map.
3. Strategies for Graceful Degradation
- Caching: serve stale data if fresh data unavailable.
- Fallbacks: switch to backup systems or reduced functionality.
- Feature flags: disable non-critical features dynamically.
- Partial results: return partial data instead of failing request.
- Circuit breakers: avoid cascading failures by cutting off failing dependencies.
4. Benefits vs Trade-offs
| Benefit | Trade-off |
|---|---|
| Improves availability | Users may see outdated data |
| Reduces downtime impact | Extra complexity to design |
| Enhances resilience | Not always possible for critical features |
5. Real-World Systems
- Netflix → Chaos Engineering tests ensure services degrade gracefully.
- Amazon → continues product browsing even if recommendation service fails.
- Slack → allows messaging even when file uploads fail.
6. Interview Tips
- Always mention graceful degradation for resiliency questions.
- Say: “If payment fails, system should still let users browse products.”
- Tie to user experience: “Better a degraded system than a down system.”
- Mention feature prioritization (critical vs optional).
7. Diagram
[ Normal Service ] → All features work.
[ Failure Detected ] → Non-critical features disabled, core continues.8. Next Steps
- Learn about Circuit Breakers, Retries, Timeouts.
- Explore Authentication & Authorization.