Sohu Smart Platform Tech Team

Feb 11, 2026 · Backend Development

Why TreeSet Throws ConcurrentModificationException and How to Fix It

An in‑depth look at why Java’s TreeSet can trigger ConcurrentModificationException under high concurrency, exploring the red‑black tree’s non‑atomic operations, thread scheduling nuances, and how various concurrent set implementations—synchronized wrappers, read‑write locks, ConcurrentSkipListSet, CopyOnWriteArraySet, and custom designs—compare in performance and suitability.