Load Testing for 2022 Spotify Wrapped
Article Summary
Spotify Wrapped serves 150M+ users in a single morning. How do you load test for that kind of thundering herd?
Spotify's engineering team shares their battle-tested approach to preparing backend infrastructure for one of the year's biggest traffic spikes. They built an internal load testing tool called Moshpit to simulate tens of millions of concurrent users hitting their systems.
Key Takeaways
- Moshpit: internal Backstage plugin that load tests using Protocol Buffers payloads
- Used employee IDs as test data for diverse, ready-to-use sample set
- Tested tens of thousands requests/second across US, EU, and Asia regions
- Coordinated upstream service scaling to prevent cascading failures during tests
- 2022 Wrapped launched without significant technical issues despite massive scale
Critical Insight
Thorough load testing with realistic payloads and cross-team coordination enabled Spotify to handle millions of simultaneous Wrapped users without breaking.
