From TCP Sockets to Unix Sockets: A Caddy Performance Case Study
· 5 min read
A recent GitHub issue #6751 in the Caddy server repository revealed a counterintuitive performance bottleneck: despite maintaining low CPU usage (1-5%), a multi-layer reverse proxy setup experienced severe throughput degradation. This investigation uncovered a critical lesson—low CPU usage doesn't guarantee performance. The culprit? Network stack overhead hiding beneath the surface. Here's what was discovered and how it was resolved.