Your Loom App Quietly Became a Thread Pool Again: A Field Guide to Virtual Thread Pinning

Thu, 16 Jul 2026 07:43:16 +0000

The incident that taught me to respect pinning looked like nothing. A service freshly migrated to virtual threads, a load test that plateaued at about 420 requests per second no matter how much traffic we threw at it, CPU sitting at 9%, zero errors, zero warnings, nothing in the logs. The machine had 8 cores, and the one downstream HTTP call in the hot path took about 19 ms. Do the arithmetic: 8 × (1000 / 19) ≈ 421.

Felipe Maschio on foojay.io - Friends of OpenJDK

Your Loom App Quietly Became a Thread Pool Again: A Field Guide to Virtual Thread Pinning