Show HN: I built a CSV parser to try Go 1.26's new SIMD package

8•tokkyokky•1w ago

Hey HN,

A CSV parser using Go 1.26's experimental simd/archsimd package.

I wanted to see what the new SIMD API looks like in practice. CSV parsing is mostly "find these bytes in a buffer"—load 64 bytes, compare, get a bitmask of positions. The interesting part was handling chunk boundaries correctly (quotes and line endings can split across chunks).

- Drop-in replacement for encoding/csv - ~20% faster for unquoted data on AVX-512 - Quoted data is slower (still optimizing) - Scalar fallback for non-AVX-512

Requires GOEXPERIMENT=simd.

https://github.com/nnnkkk7/go-simdcsv

Feedback on edge cases or the SIMD implementation welcome.

Comments

zigzag312•1w ago

Benchmark comparison with C# SIMD optimized CSV parser [1] would be fun to see.

[1] https://github.com/nietras/Sep

tokkyokky•1w ago

Oh, nice! I’ll try to do it!!

juliusgeo•1w ago

This is super cool! If I'm understanding your implementation correctly, you do perform bit by bit state machine logic to check whether quotes should be escaped etc. You can do that in a single pass by using carry-less polynomial multiplication instructions (_mm_clmulepi64_si128 on AVX-512 I believe), or by just computing the carryless xor directly on the quote mask and then &ing the inverse with the bitmask for quotes. Simdjson uses this trick, and I use it as well in my Rust simd csv parser:

https://github.com/juliusgeo/csimdv-rs/blob/681df3b036f30c5a...

This is a good write-up on how the approach works: https://nullprogram.com/blog/2021/12/04/

tokkyokky•1w ago

Thanks for the tip! Your comment prompted me to refactor the quote handling - replaced the bit-by-bit state machine loop with prefix XOR, and switched to adjacent bit masking for double-quote detection. Seeing a nice performance improvement in benchmarks. Go's simd/archsimd doesn't have CLMUL yet, but the XOR cascade works well. Appreciate your feedback!

Show HN: Look Ma, No Linux: Shell, App Installer, Vi, Cc on ESP32-S3 / BreezyBox

Show HN: Kappal – CLI to Run Docker Compose YML on Kubernetes for Local Dev

Show HN: I spent 4 years building a UI design tool with only the features I use

Show HN: If you lose your memory, how to regain access to your computer?

Show HN: MCP App to play backgammon with your LLM

Show HN: R3forth, a ColorForth-inspired language with a tiny VM

Show HN: Smooth CLI – Token-efficient browser for AI agents

Show HN: I'm 75, building an OSS Virtual Protest Protocol for digital activism

Show HN: I built Divvy to split restaurant bills from a photo

Show HN: BioTradingArena – Benchmark for LLMs to predict biotech stock movements

Show HN: ARM64 Android Dev Kit

Show HN: Slack CLI for Agents

Show HN: Artifact Keeper – Open-Source Artifactory/Nexus Alternative in Rust

Show HN: I Hacked My Family's Meal Planning with an App

Show HN: I built a free UCP checker – see if AI agents can find your store

Show HN: Gigacode – Use OpenCode's UI with Claude Code/Codex/Amp

Show HN: Compile-Time Vibe Coding

Show HN: Daily-updated database of malicious browser extensions

Show HN: Micropolis/SimCity Clone in Emacs Lisp

Show HN: Slop News – HN front page now, but it's all slop

Show HN: Horizons – OSS agent execution engine

Show HN: Falcon's Eye (isometric NetHack) running in the browser via WebAssembly

Show HN: Fitspire – a simple 5-minute workout app for busy people (iOS)

Show HN: Local task classifier and dispatcher on RTX 3080

Show HN: I built a RAG engine to search Singaporean laws

Show HN: Sem – Semantic diffs and patches for Git

Show HN: A password system with no database, no sync, and nothing to breach

Show HN: GitClaw – An AI assistant that runs in GitHub Actions

Show HN: FastLog: 1.4 GB/s text file analyzer with AVX2 SIMD

Show HN: Craftplan – I built my wife a production management tool for her bakery