Performance monitoring in Mercari mobile apps
Article Summary
Mercari rewrote their entire mobile app and faced a nightmare scenario: millions of users reporting the new version felt slower than the old one.
Francesco Pretelli from Mercari's mobile architects team shares how they built a comprehensive performance monitoring system during their GroundUP rewrite. The challenge was ensuring the new app (built with SwiftUI and Jetpack Compose) matched or exceeded the performance of the legacy version.
Key Takeaways
- Identified 9 core business scenarios and manually measured load times first
- Weekly pre-release benchmarks now block releases if performance thresholds aren't met
- Datadog RUM enables end-to-end tracing from client to backend microservices
- Performance dashboards with automated alerts catch degradation before users complain
- Controlled benchmarks plus real production monitoring create complete visibility
Critical Insight
Mercari built a two-pronged performance system combining weekly in-house benchmarks with production monitoring that traces performance issues from mobile UI through to backend services.
