False sharing

A concurrency performance pathology where logically independent variables land on the same CPU cache line, so writes from different cores trigger needless cache-coherence invalidations that serialize otherwise-parallel work.

grounded in: HN front-page theme 'Rust and the hard edges of systems concurrency: Rust's model and async concurrency pitfalls are a recurring engineering discussion'

Connected concepts

Memory ordering, Lock-free programming, Thread-per-Core, Memory-bandwidth-bound decode