github.com/pixeldrama/go-heap-performance

Heap vs Stack Performance

Call By Value and Call by Reference

• Call by value default for datatypes: int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, uintptr, float32, float64, string, bool, byte, rune, Array, Structs
• Slices and Maps are Called by Reference by default
• Receiver functions

Stack vs Heap

• Call by value does not use the heap, no GC involved here
• Call by reference could use the heap, it is not always the case

Execution

go build -gcflags '-m -l' # -m print decisions from compile, -l avoid inlining
go test -bench=. -benchmem 

Some Take Away

• Call by seems to be faster in our artificial example
• API-Design mutability should not be mixed
• No absense value is possible (like nil), typical solution is to wrap it into a struct:

type Counter struct {
    valid boolean
    i int
}

References

• Benchmarking Generics in Go
• Golang Pass by value vs Pass by reference
• Understanding Allocations in Go
• When to use Pointers