Arkadiusz Przychocki on foojay.io - Friends of OpenJDK

Your TLS Stack Is Lying to You About Zero-Copy

Wed, 10 Jun 2026 12:00:28 +0000

The “No Waste Compute” Constraint

When I started designing the Exeris Kernel, I set one non-negotiable rule very early: no waste compute. That rule sounds like a performance slogan until it starts killing otherwise normal design decisions.

I had already banned ThreadLocal, moved context propagation to Scoped Values, and pushed more of the runtime into explicit off-heap ownership. The idea was simple: if the hot path is supposed to stay outside GC pressure, then memory shape and lifetime cannot be treated as incidental details.

Scoped Values: Why I Banned ThreadLocal in Exeris

Thu, 28 May 2026 09:36:00 +0000

In a zero-copy runtime designed for 1-VT-per-Stream density, ThreadLocal is a performance serial killer. Here is the forensic analysis and how JEP 506 Scoped Values changed everything.

When I started designing the Exeris Kernel — a next-generation, zero-copy runtime built for Java 26+ — I established one non-negotiable architectural law: “No Waste Compute.”

In a system designed to handle extreme density by mapping exactly one Virtual Thread to every network stream (1-VT-per-Stream), every byte of memory and every CPU cycle must be intentional.