Golang byte 拼接方法性能对比

package main
import (
	"bytes"
	"fmt"
	"time"
)
func main() {
	count := 1000000
	oneSerail := []byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
	s0 := time.Now()
	for i := 0; i < count; i++ {
		str0 := make([][]byte, 8)
		str0[0] = oneSerail[0:4]
		str0[1] = oneSerail[4:6]
		str0[2] = oneSerail[6:10]
		str0[3] = oneSerail[0:2]
		str0[4] = oneSerail[2:6]
		str0[5] = oneSerail[6:8]
		str0[6] = oneSerail[0:4]
		str0[7] = oneSerail[8:10]
		bytes.Join(str0, []byte(""))
	}
	e0 := time.Now()
	d0 := e0.Sub(s0)
	fmt.Printf("time of way(0)=%v\n", d0)
	s1 := time.Now()
	for i := 0; i < count; i++ {
		str1 := make([]byte, 0)
		str1 = append(str1, oneSerail[0])
		str1 = append(str1, oneSerail[1])
		str1 = append(str1, oneSerail[2])
		str1 = append(str1, oneSerail[3])
		str1 = append(str1, oneSerail[4])
		str1 = append(str1, oneSerail[5])
		str1 = append(str1, oneSerail[6])
		str1 = append(str1, oneSerail[7])
		str1 = append(str1, oneSerail[8])
		str1 = append(str1, oneSerail[9])
		str1 = append(str1, oneSerail[0])
		str1 = append(str1, oneSerail[1])
		str1 = append(str1, oneSerail[2])
		str1 = append(str1, oneSerail[3])
		str1 = append(str1, oneSerail[4])
		str1 = append(str1, oneSerail[5])
		str1 = append(str1, oneSerail[6])
		str1 = append(str1, oneSerail[7])
		str1 = append(str1, oneSerail[8])
		str1 = append(str1, oneSerail[9])
		str1 = append(str1, oneSerail[0])
		str1 = append(str1, oneSerail[1])
		str1 = append(str1, oneSerail[2])
		str1 = append(str1, oneSerail[3])
		str1 = append(str1, oneSerail[4])
		str1 = append(str1, oneSerail[5])
		str1 = append(str1, oneSerail[6])
		str1 = append(str1, oneSerail[7])
		str1 = append(str1, oneSerail[8])
		str1 = append(str1, oneSerail[9])
	}
	e1 := time.Now()
	d1 := e1.Sub(s1)
	fmt.Printf("time of way(1)=%v\n", d1)
	s2 := time.Now()
	for i := 0; i < count; i++ {
		str2 := make([]byte, 0)
		str2 = append(str2, oneSerail[0:4]...)
		str2 = append(str2, oneSerail[4:6]...)
		str2 = append(str2, oneSerail[6:10]...)
		str2 = append(str2, oneSerail[0:2]...)
		str2 = append(str2, oneSerail[2:6]...)
		str2 = append(str2, oneSerail[6:8]...)
		str2 = append(str2, oneSerail[0:4]...)
		str2 = append(str2, oneSerail[4:8]...)
		str2 = append(str2, oneSerail[8:10]...)
	}
	e2 := time.Now()
	d2 := e2.Sub(s2)

	fmt.Printf("time of way(2)=%v\n", d2)

	s3 := time.Now()

	for i := 0; i < count; i++ {
		str3 := make([]byte, 30)
		for j := 0; j < 30; j++ {
			str3[j] = oneSerail[j%10]
		}
	}
	e3 := time.Now()
	d3 := e3.Sub(s3)
	fmt.Printf("time of way(3)=%v\n", d3)
}

运行结果如下：

time of way(0)=152.2175ms
time of way(1)=141.7367ms
time of way(2)=125.7664ms
time of way(3)=69.8702ms

结果分析：
1，bytes.Join耗时最久，可能是因为在进行Join的时候需要进行重新内存分配导致；
2，单byte进行append耗时比bytes.Join短，但是有限；
3，[]byte…进行append的耗时比1和2短，因为append操作的次数比2少很多；
4，最快的方法，但是需要预知拼接后byte组的大小；

总结：golang的内存分配真的很耗时。