Search across all documentation pages
Choosing types and memory layouts in Go balances readability, correctness under concurrency, and measured performance. These rules turn the internals articles in this section into day-to-day engineering habits.
pprof) before changing types for speed.time.Time, IDs, coordinates). Avoid hidden mutation and nil checks.[]T over arrays in public APIs unless size is protocol-fixed. Arrays complicate generics and function boundaries.map[K]V only with comparable keys; never float keys. Sets use map[T]struct{} for clarity.make([]T, 0, n) and make(map[K]V, n) when size is known. Cuts growth and rehash cost in loaders and parsers.append from mutating your internal buffers.make or literals. Nil reads are fine; writes panic.maps.Clone) before async processing. Avoid races on shared map mutations.nil error, not typed nil pointers, from constructors. err == nil must mean success.any. Prevent panics on unexpected dynamic types.interface{} at boundaries; decode to concrete types early. Narrow scope of dynamic dispatch and reflection costs.sync.Map for specific caches. Concurrent map writes are undefined.go test -race on packages sharing memory between goroutines. Catches unsynchronized slice/map/pointer access.range or ok to exit cleanly.context.Context for cancel, not ad-hoc bool flags alone. Pair with channel/select shutdown paths.unsafe.Sizeof tests and ABI awareness. Padding changes affect FFI and on-disk formats.unsafe only after benchmarks prove need. Isolate in small functions with documented invariants.-gcflags=-m) after allocation regressions. Unexpected heap traffic often starts at pointer escapes.sync.Pool for transient slices, not long-lived state. Avoid retaining large backing arrays accidentally.Values for small immutable records; pointers for large or mutable shared state. When unsure, start with values and profile hot paths.
Sharing subslices with spare capacity, then appending into caller-owned memory. Copy or use three-index slicing.
Concurrent writes without synchronization. Use mutex sharding or pass snapshots to worker goroutines.
Returning typed nil pointers as error. Return bare nil on success paths from constructors.
cgo/syscall interop, proven zero-copy bottlenecks, and stdlib-style primitives with tests per platform - never for convenience.
Size to the burst you want to absorb without unbounded memory; default unbuffered when synchronization is the goal.
make for slices, maps, channels; literals or var for structs. new is rare in idiomatic Go application code.
Replace with a new map periodically or scope maps to request/generation lifetime instead of unbounded growth.
Often for len/append, but JSON and some APIs differ. Use make([]T, 0) when you need non-nil empty semantics.
go test -race, go vet, golangci-lint, and periodic alloc/cpu profiles on representative workloads.
Generics reduce hot-path interface boxing; interfaces remain for heterogeneous plugin boundaries and stdlib patterns.
Read the section articles on slices, maps, interfaces, channels, and the memory model explainer in order.
Stack versions: This page was written for Go 1.26.x (Green Tea GC default, go fix modernizers - verify patch at build), chi (latest - verify at build), gin (latest - verify at build), echo (latest - verify at build), google.golang.org/grpc (latest - verify at build), sigs.k8s.io/controller-runtime (latest - verify at build), kubebuilder (latest - verify at build), tinygo (latest - verify board targets at build), wazero (latest - verify at build), and golangci-lint (latest - verify linter set at build).
Reviewed by Chris St. John·Last updated Jul 16, 2026