I worked on Pinterest Related Pins 2015–2017, as tech lead and later as engineering manager. In 2017 we published this paper at the World Wide Web conference in Perth, Australia. It describes in detail the progression of Related Pins over time.
Related Pins at Pinterest: The Evolution of a Real-World Recommender System
David C. Liu, Stephanie Rogers, Raymond Shiau, Dmitry Kislyuk, Kevin C. Ma, Zhigang Zhong, Jenny Liu, Yushi Jing
Abstract: Related Pins is the Web-scale recommender system that powers over 40% of user engagement on Pinterest. This paper is a longitudinal study of three years of its development, exploring the evolution of the system and its components from prototypes to present state. Each component was originally built with many constraints on engineering effort and computational resources, so we prioritized the simplest and highest-leverage solutions. We show how organic growth led to a complex system and how we managed this complexity. Many challenges arose while building this system, such as avoiding feedback loops, evaluating performance, activating content, and eliminating legacy heuristics. Finally, we offer suggestions for tackling these challenges when engineering Web-scale recommender systems.