benchmark for strings.Join and string appending

benchmark_for_strings_Join_vs_string_appending.go

package main

import (
	"strconv"
	"strings"
	"testing"
)

const sliceLen = 1000

func buildWithStringsJion() string {
	l := make([]string, sliceLen, sliceLen)
	for i := 0; i < 1000; i++ {
		l[i] = strconv.Itoa(i)
	}

	return strings.Join(l, ",")
}

func buildWithStringAppending() string {
	s := ""
	for i := 0; i < 1000; i++ {

		if i == 0 {
			s = strconv.Itoa(i)
		} else {
			s += "," + strconv.Itoa(i)
		}
	}

	return s
}

func BenchmarkBuildWithStringsJoin(b *testing.B) {
	for i := 0; i < b.N; i++ {
		buildWithStringsJion()
	}
}

func BenchmarkBuildWithStringAppending(b *testing.B) {
	for i := 0; i < b.N; i++ {
		buildWithStringAppending()
	}
}

// $go test -bench . -benchmem
// output #=>
// goos: darwin
// goarch: amd64
// pkg: github.com/Focinfi/GolangPractices/learn-awesome-project/strings
// BenchmarkBuildWithStringsJoin-4       	   50000	     37925 ns/op	   11072 B/op	     902 allocs/op
// BenchmarkBuildWithStringAppending-4   	    5000	    309293 ns/op	 2033473 B/op	    1899 allocs/op
// PASS
// ok  	github.com/Focinfi/GolangPractices/learn-awesome-project/strings	3.870s