ByteDance SE Lab

Apr 3, 2026 · Fundamentals

Douyin’s Deep Dive: Expanding Android ART Heap, FD Limits & M:N Threading on Legacy Devices

This article details how Douyin engineers tackled Android’s limited heap, file‑descriptor, and thread constraints on older phones by expanding ART malloc and region spaces, enlarging FD/FD_SET limits, and implementing a transparent M:N user‑level threading model, achieving significant stability and performance gains.