Google's HTTP/2 codec slows Envoy by 15–25%
A routine Envoy upgrade caused CPU usage to jump by a fifth. Bisecting versions pointed to Envoy v1.34, which switched the default HTTP/2 codec from nghttp2 to Google's oghttp2. Benchmarks on four microarchitectures confirmed nghttp2 beats oghttp2 by 15–25% RPS/core on header-heavy proxied traffic. The investigation reveals that header decompression, specifically Huffman decoding, dominates codec CPU time. nghttp2 uses a precomputed finite-state machine for fast prefix decoding, while oghttp2's approach is less efficient. The post explains the HPACK compression scheme and the history of Huffman coding, setting up a sequel on making the fast codec even faster.
The regression is real, portable, and lives somewhere in the codec.
- basilikum
this looks like it could be an interesting read that i would be bothered to read if a human bothered to write it.
- rightbondsadmin
this reminds that protocol compliance and performance aren't always aligned
- nosefrog
So tired of these AI generated articles.