Writing Benchmarks – `testing.B`

Benchmark Example

This lesson explains the main concept clearly with beginner-friendly examples and background so you can learn why the code works.

func BenchmarkEncodeJSON(b *testing.B) {
    obj := map[string]int{"a":1,"b":2,"c":3}
    for i := 0; i < b.N; i++ {
        json.Marshal(obj)
    }
}

Run with:

$ go test -bench=. -benchmem

The output shows ns/op, allocs/op, and B/op.

Controlling benchmark size

func BenchmarkMultiply(b *testing.B) {
    for i := 0; i < b.N; i++ { multiply(12345, 6789) }
}

Use b.ResetTimer() after any preparatory work.