Why Use Unfair Locks? Java Implementation and Performance Benefits

This article explains what unfair locks are, why they can improve throughput compared to fair locks, provides a Java ReentrantLock example with code, describes the internal acquisition process, and outlines typical high‑concurrency scenarios where unfair locks are advantageous.

ReentrantLockUnfair Lockconcurrency

0 likes · 5 min read

Why Use Unfair Locks? Java Implementation and Performance Benefits

Youzan Coder

Jul 8, 2020 · Backend Development

Druid Connection Pool Performance Optimization: Fair Lock vs Unfair Lock

The article explains how a Druid 1.1.20 connection pool was throttled to ~10k RPS by fair‑locking in recycle(), and how enabling the unfair lock (setUseUnfairLock(true)) doubled single‑machine TPS, raised CPU usage to near 100 % and boosted cluster throughput by about 70 %.

ArthasDruidJava concurrency

0 likes · 7 min read

Druid Connection Pool Performance Optimization: Fair Lock vs Unfair Lock