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Experimentation

1 post · Jan 2014

What this trail covers

Meta's mobile A/B testing framework, Airlock, evolved to support native iOS and Android development. It addresses challenges in coordinating feature releases, comparing metric data across app versions, and ensuring data integrity through a two-way handshake between client and server. The system scales to support numerous experiments and variations, with optimizations for cold-start performance and minimized data flow. Airlock enables the testing of UI changes, feature performance, and reliability improvements, allowing for iterative development and informed shipping decisions.

All Meta trails
  1. Airlock – Facebook’s mobile A/B testing frameworkThis post details the creation and evolution of Airlock, Facebook's mobile A/B testing framework. It describes the initial challenges of losing A/B testing capabilities after migrating to native iOS and Android development stacks. The post outlines the core components of Airlock, including server-side experiment parameter requests, client-side storage and UI reconfiguration, and exposure logging. A key failure mode identified was incorrect caching logic on the client, leading to discrepancies between server-assigned variants and actual user exposure. The solution involved implementing a two-way handshake for more reliable data logging and analysis. The post also discusses scaling Airlock to support multiple experiments and variations, the importance of isolating experiments, and optimizing for cold-start performance and server-client interaction.