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App Size Management

4 posts · Apr 2020 – Oct 2023

What this trail covers

Spotify is actively managing and optimizing application size across its mobile platforms. This involves implementing pre-merge checks using tools like Emerge to analyze the impact of code changes on download and install sizes, with a 50KB threshold for additional review. Post-merge, a dedicated Slack channel tracks significant size changes. To address gradual, 'under the radar' growth, Spotify is evaluating compilation unit and resource file sizes, attributing them to owning teams via Emerge's C. This post details a significant modernization of the client-side architecture to improve the listening experience on all devices, particularly addressing performance issues on older phones and slower networks by optimizing how Liked Songs metadata is loaded and stored locally. This involved a substantial refactoring of the client codebase, replacing in-memory sorting with pre-computed tables stored on disk, and implementing batched downloads.

All Spotify trails
  1. The What, Why, and How of Mastering App SizeThis post details Spotify's multi-faceted approach to managing app size. It introduces pre-merge checks using Emerge Tools to analyze PR impact on app size, with a 50KB threshold for manual review. A post-merge Slack channel tracks significant size changes. For ongoing growth, it describes using Emerge's Compilation Unit Attribution and in-house scripts to evaluate compilation unit and resource file sizes, attributing them to owning teams. This data is visualized in Backstage for team accountability and comparison. The post also discusses the inherent trade-offs in app size optimization.
  2. Introducing Ruler: Our Tool for Measuring Android App SizeThis post introduces Ruler, an open-sourced Gradle plugin designed to measure and analyze the size of Android apps. Ruler works by replicating the App Bundle to APK generation process using Bundletool, then analyzing the APK with apkanalyzer to capture download and install sizes for individual files. It determines file origins by scanning Gradle modules and dependencies, and can also parse DEX files to approximate individual class sizes. Ruler supports ownership data to attribute app size contributions to specific teams and has been used at Spotify to reduce app size by over 9%.
  3. How We Built It: Spotify Lite, One Year LaterThis post details the engineering challenges and solutions involved in building Spotify Lite, a separate, smaller version of the Spotify app for users with constrained resources. Key contributions include: building a new app from scratch with a different playback stack for minimal memory and network usage; implementing extensive binary size reduction techniques (e.g., using the lld linker, link time code optimizations, R8 shrinking, App Bundles, stripping unused translations); allowing users to store app and cache/downloads on SD cards; and generalizing backend services to identify and serve different Spotify apps (Lite, Kids, Stations, Android Automotive). The post also highlights the iterative process of balancing feature additions with maintaining a small app size and the introduction of continuous delivery pipeline checks for size bloat.
  4. Spotify Modernizes Client-Side Architecture to Accelerate Service on All DevicesThis post details a significant modernization of the client-side architecture to improve the listening experience on all devices, particularly addressing performance issues on older phones and slower networks by optimizing how Liked Songs metadata is loaded and stored locally. This involved a substantial refactoring of the client codebase, replacing in-memory sorting with pre-computed tables stored on disk, and implementing batched downloads. The project required modifying approximately 100,000 lines of code in the shared client codebase and tweaking both Android and iOS apps to ensure feature parity and support for new UI trends.