go生成唯一的随机数

package main

import (
    "crypto/rand"
    "fmt"
    "math/big"
    "strconv"
    "sync"
    "time"
)

func main() {

    wg := sync.WaitGroup{}
    fmt.Println("go start", time.Now())

    var arr = []string{}

    for i := 0; i < 300; i++ {
        wg.Add(1)
        go func() {
            n, _ := rand.Int(rand.Reader, big.NewInt(100000000))
            arr = append(arr, strconv.FormatInt(n.Int64()+time.Now().UnixNano(), 10))
            wg.Done()
        }()
    }
    wg.Wait()
    fmt.Println(arr)
}