Client Tracing: Understanding Mobile and Desktop Application Performance at Scale

This post details the foundational work to implement client-side tracing for Slack's mobile and desktop applications (iOS, Android, JavaScript). It explains how distributed tracing concepts are applied to client performance analysis, breaking down API requests into queue time, HTTP request time, and parse time. It also details how database operations are traced, including wait time, execution time, and save time. The post introduces a custom Client Tracing API designed for client-specific needs and discusses production rollout strategies and sampling.