golang 1.10 strings builder test

result.txt

$ go test -bench . -benchmem
goos: linux
goarch: amd64
pkg: github.com/knsh14/sample
BenchmarkBytesBuffer-2                        10         103512777 ns/op        438779214 B/op            23 allocs/op
BenchmarkStringBuilder-2                      10         138950789 ns/op        661977072 B/op            54 allocs/op
BenchmarkBytesBufferString-2             5000000               353 ns/op            1280 B/op              1 allocs/op
BenchmarkStringBuilderString-2          2000000000               0.33 ns/op            0 B/op              0 allocs/op
PASS
ok      github.com/knsh14/sample  5.699s

sample.go

package main

import (
	"bytes"
	"strings"
)

func BytesBuffer() string {
	var out bytes.Buffer
	for i := 0; i < 1000000; i++ {
		out.WriteString("hello world\n")
	}
	return out.String()
}

func StringBuilder() string {
	var out strings.Builder
	for i := 0; i < 1000000; i++ {
		out.WriteString("hello world\n")
	}
	return out.String()
}

func NewBytesBuffer() bytes.Buffer {
	var out bytes.Buffer
	for i := 0; i < 100; i++ {
		out.WriteString("hello world\n")
	}
	return out
}

func NewStringBuilder() strings.Builder {
	var out strings.Builder
	for i := 0; i < 100; i++ {
		out.WriteString("hello world\n")
	}
	return out
}

sample_test.go

package main

import "testing"

func BenchmarkBytesBuffer(b *testing.B) {
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = BytesBuffer()
	}
}
func BenchmarkStringBuilder(b *testing.B) {
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = StringBuilder()
	}
}

func BenchmarkBytesBufferString(b *testing.B) {
	v := NewBytesBuffer()
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = v.String()
	}
}
func BenchmarkStringBuilderString(b *testing.B) {
	v := NewStringBuilder()
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = v.String()
	}
}