Demonstrates that the string representation of an int64 requires twice the memory

string_vs_int_test.go

package typesizes

import (
	"math"
	"strconv"
	"testing"
)

var N int = 1e7
var stringSize int = 1 + int(math.Log10(float64(N)))

func TestStringAndInt(b *testing.T) {
	var x []int64
	var y []string

	for i := 0; i < N; i++ {
		x = append(x, int64(i))
		y = append(y, strconv.Itoa(i))
	}
}

// 22:29:22 ~/workspace/gocode/src/playground/typesizes 86$ go test -test.run=And -memprofile=mem.out -memprofilerate=1024 -test.v && go tool pprof --alloc_space typesizes.test mem.out
// === RUN   TestStringAndInt
// --- PASS: TestStringAndInt (7.68s)
// PASS
// ok      playground/typesizes    7.779s
// Entering interactive mode (type "help" for commands)
// (pprof) top
// 1269.12MB of 1269.16MB total (  100%)
// Dropped 21 nodes (cum <= 6.35MB)
//       flat  flat%   sum%        cum   cum%
//  1193.08MB 94.01% 94.01%  1269.12MB   100%  playground/typesizes.TestStringAndInt
//    76.04MB  5.99%   100%    76.04MB  5.99%  strconv.formatBits
//          0     0%   100%  1269.15MB   100%  runtime.goexit
//          0     0%   100%    76.04MB  5.99%  strconv.FormatInt
//          0     0%   100%    76.04MB  5.99%  strconv.Itoa
//          0     0%   100%  1269.12MB   100%  testing.tRunner
// (pprof) list And
// Total: 1.24GB
// ROUTINE ======================== playground/typesizes.TestStringAndInt in /Users/jpirruccello/workspace/gocode/src/playground/typesizes/main_test.go
//     1.17GB     1.24GB (flat, cum)   100% of Total
//          .          .     13:func TestStringAndInt(b *testing.T) {
//          .          .     14:   var x []int64
//          .          .     15:   var y []string
//          .          .     16:
//          .          .     17:   for i := 0; i < N; i++ {
//   403.88MB   403.88MB     18:           x = append(x, int64(i))
//   789.20MB   865.23MB     19:           y = append(y, strconv.Itoa(i))
//          .          .     20:   }
//          .          .     21:}