Golang 字符串拼装方式性能对比

Go语言中字符串的拼装方法很多,那么问题来了,到底哪家性能好?

下面代码,分别比较了 fmt.Sprintf,string +,strings.Join,bytes.Buffer,方法是循环若干次比较总时间。在VMWare下的Ubuntu 14.04下运行的结果如下,仅供参考:

• fmt.Sprintf 和 strings.Join 速度相当
• string + 比上述二者快一倍
• bytes.Buffer又比上者快约400-500倍
• 如果循环内每次都临时声明一个bytes.Buffer来使用,会比持续存在慢50%,但是仍然很快

测试代码如下:

package main
import (
 "bytes"
 "fmt"
 "strings"
 "time"
)
func benchmarkStringFunction(n int, index int) (d time.Duration) {
 v := "ni shuo wo shi bu shi tai wu liao le a?"
 var s string
 var buf bytes.Buffer
 t0 := time.Now()
 for i := 0; i < n; i++ {
 switch index {
 case 0: // fmt.Sprintf
 s = fmt.Sprintf("%s[%s]", s, v)
 case 1: // string +
 s = s + "[" + v + "]"
 case 2: // strings.Join
 s = strings.Join([]string{s, "[", v, "]"}, "")
 case 3: // temporary bytes.Buffer
 b := bytes.Buffer{}
 b.WriteString("[")
 b.WriteString(v)
 b.WriteString("]")
 s = b.String()
 case 4: // stable bytes.Buffer
 buf.WriteString("[")
 buf.WriteString(v)
 buf.WriteString("]")
 }
 if i == n-1 {
 if index == 4 { // for stable bytes.Buffer
 s = buf.String()
 }
 fmt.Println(len(s)) // consume s to avoid compiler optimization
 }
 }
 t1 := time.Now()
 d = t1.Sub(t0)
 fmt.Printf("time of way(%d)=%v\n", index, d)
 return d
}
func main() {
 k := 5
 d := [5]time.Duration{}
 for i := 0; i < k; i++ {
 d[i] = benchmarkStringFunction(10000, i)
 }
 for i := 0; i < k-1; i++ {
 fmt.Printf("way %d is %6.1f times of way %d\n", i, float32(d[i])/float32(d[k-1]), k-1)
 }
}

其中一次的结果如下:

410000
time of way(0)=1.199641573s
410000
time of way(1)=568.716669ms
410000
time of way(2)=1.197077483s
41
time of way(3)=2.277063ms
410000
time of way(4)=1.398864ms
way 0 is 857.6 times of way 4
way 1 is 406.6 times of way 4
way 2 is 855.7 times of way 4
way 3 is 1.6 times of way 4

本文来自:开源中国博客

感谢作者:吃一堑消化不良

查看原文:Golang 字符串拼装方式性能对比

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