#Go comparison bench

Apples-to-apples microbenchmarks against bench/bench.lua so the LuaJIT runtime can be compared to mainstream Go protobuf implementations.

#What it measures

Same fixtures and size sweep as the Lua bench:

• hello.Person at five payload sizes (10 B, 100 B, 1 KB, 10 KB, 100 KB)
• proto2_basic.BenchPayload at two sizes (min, mid)

For each fixture × size, both encode and decode under two Go implementations:

• apiv2 — google.golang.org/protobuf/proto.Marshal/Unmarshal. The default reflective marshaler everyone gets out of the box.
• vtproto — planetscale/vtprotobuf generated MarshalVT/UnmarshalVT. Code-gen'd, no reflection. Conceptually equivalent to our mode=full Lua codegen.

Single-threaded: Go's testing.B runs serially unless RunParallel is called. -cpu=1 is not needed — GOMAXPROCS only affects GC parallelism, not bench iterations.

#Running

just bench-go                          # full sweep, default benchtime=1s
cd bench/go && go test -bench=Person -benchtime=3s ./...

go test reports ns/op, MB/s (via b.SetBytes), B/op, allocs/op.

#Comparing to the Lua bench

bench/bench.lua --print emits ns/op + msgs/s + MB/s + bytes/op per mode × size. Run both, pick the same size, compare directly. The encoded byte lengths should match within a byte or two for the same target size since both use the same proto definitions and equivalent payload builders.

#proto2 caveats

• Extensions skipped by vtproto. MarshalVT does not serialize proto2 extensions, so the BenchPayload fixture (which carries ext_count + ext_label) would produce shorter bytes than the apiv2 path. The vtproto proto2 cases are intentionally omitted to avoid publishing misleading throughput numbers.
• Groups are supported by both protoc-gen-go and vtproto.

#Layout

bench/go/
├── go.mod
├── proto/                  # .proto sources (subset of repo protos with go_package set)
├── pb/{hellopb,proto2pb}/  # generated *.pb.go + *_vtproto.pb.go
├── fixtures.go             # payload builders mirroring bench/bench.lua
└── bench_test.go           # `go test -bench` entry points

#Generated .pb.go files

*.pb.go is gitignored repo-wide, so bench/go/pb/ is not committed — regenerate locally before running the bench:

just gen-go      # runs protoc with both plugins; bench-go depends on it

Requires protoc-gen-go and protoc-gen-go-vtproto on $PATH:

go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
go install github.com/planetscale/vtprotobuf/cmd/protoc-gen-go-vtproto@latest