Show HN: go-binsync – Go binary patches up to 67× smaller than bsdiff

This project is a little performance-optimization experiment focused on reducing the size of Go binary patches, which can be useful for quick incremental updates of live services.

When a Go program grows by a few bytes through an incremental change, a bunch of related references and offsets throughout the compiled binary end up changing that makes general-purpose binary-diff encoders inefficient: `zstd --patch-from` produces a 530kb patch for a one-line change in a 30MB binary. bsdiff improves upon this (150KB patch) thanks to a delta compression algorithm that can handle relative offsets.

go-binsync goes a step further for Go binaries by borrowing an idea from Courgette, the technique Google uses to ship Chrome updates: read the structure the compiler left behind, predict the expected results from that structure, and send only the correction. Courgette gets that structure by disassembling; go-binsync gets more detailed Go-specific structure from additional metadata embedded in every compiled Go binary.

The end result is a 2,262-byte patch for the one-line change, or a 67× improvement over the bsdiff result. (For a less synthetic result, a Prometheus 3.13.1 - 3.13.2 patch is still 28× smaller.)

Still just a proof of concept (no CGO, no debug symbols, amd64 only) but I thought others might find the initial results interesting. I think this predictive-encoding approach could be generalized beyond Go binaries to efficient compression in other domains where some kind of specialized predictive structure is available.