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下运行的结果表明:
- 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:
etworker@ubuntu:~/work/go/test$ go run testBenchmark.go 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
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