字符串拼接方式性能对比

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测试

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package performance_test

import (
	"bytes"
	"fmt"
	"strings"
	"testing"
)

const v string = "ni shuo wo shi bu shi tai wu liao le a?"

func BenchmarkTest1(b *testing.B) {
	var s string
	for i := 0; i < b.N; i++ {
		s = fmt.Sprintf("%s[%s]", s, v)
	}
}

func BenchmarkTest2(b *testing.B) {
	var s string
	for i := 0; i < b.N; i++ {
		s = strings.Join([]string{s, "[", v, "]"}, "")
	}
}

func BenchmarkTest3(b *testing.B) {
	buf := bytes.Buffer{}
	for i := 0; i < b.N; i++ {
		buf.WriteString("[")
		buf.WriteString(v)
		buf.WriteString("]")
	}
}

func BenchmarkTest4(b *testing.B) {
	var s string
	for i := 0; i < b.N; i++ {
		s = s + "[" + v + "]"
	}
}

go test -v -test.bench=”.” -benchmem String_concatenation_test.go 

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goos: darwin
goarch: amd64
BenchmarkTest1-4           50000            171597 ns/op         2063850 B/op          4 allocs/op
BenchmarkTest2-4           50000            137827 ns/op         1029071 B/op          1 allocs/op
BenchmarkTest3-4        20000000                85.8 ns/op            86 B/op          0 allocs/op
BenchmarkTest4-4           50000             87791 ns/op         1029071 B/op          1 allocs/op
PASS
ok      command-line-arguments  22.715s

结论

  • 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

参考资料:

golang 几种常见的字符串连接性能比较