我正在为我的并行课程做一个小项目，我尝试了使用带缓冲通道、无缓冲通道、使用指向切片的指针的无缓冲通道等。此外，我还尝试尽可能优化它（不是当前状态），但我仍然得到相同的结果：增加goroutine的数量（甚至是1个）会降低整个程序的运行速度，有人能告诉我我做错了什么吗？在这种情况下，并行性增强是可能的吗？
下面是部分代码：

func main() {

    rand.Seed(time.Now().UnixMicro())

    numAgents := 2

    fmt.Println("Please pick a number of goroutines: ")
    fmt.Scanf("%d", &numAgents)

    numFiles := 4
    fmt.Println("How many files do you want?")
    fmt.Scanf("%d", &numFiles)
    start := time.Now()

    numAssist := numFiles
    channel := make(chan []File, numAgents)
    files := make([]File, 0)

    for i := 0; i < numAgents; i++ {
        if i == numAgents-1 {
            go generateFiles(numAssist, channel)
        } else {
            go generateFiles(numFiles/numAgents, channel)
            numAssist -= numFiles / numAgents
        }
    }

    for i := 0; i < numAgents; i++ {
        files = append(files, <-channel...)
    }

    elapsed := time.Since(start)
    fmt.Printf("Function took %s\n", elapsed)
}

func generateFiles(numFiles int, channel chan []File) {
    magicNumbersMap := getMap()
    files := make([]File, 0)

    for i := 0; i < numFiles; i++ {
        content := randElementFromMap(&magicNumbersMap)

        length := rand.Intn(400) + 100
        hexSlice := getHex()

        for j := 0; j < length; j++ {
            content = content + hexSlice[rand.Intn(len(hexSlice))]
        }

        hash := getSHA1Hash([]byte(content))

        file := File{
            content: content,
            hash:    hash,
        }

        files = append(files, file)
    }

    channel <- files

}

我们的期望是通过增加goroutine的数量程序会运行得更快，但是当goroutine的数量达到一定值时，我会得到相同的执行时间或者稍微慢一点.
编辑：使用的所有函数：

import (
    "crypto/sha1"
    "encoding/base64"
    "fmt"
    "math/rand"
    "time"
)

type File struct {
    content string
    hash    string
}

func getMap() map[string]string {
    return map[string]string{
        "D4C3B2A1": "Libcap file format",
        "EDABEEDB": "RedHat Package Manager (RPM) package",
        "4C5A4950": "lzip compressed file",
    }
}

func getHex() []string {
    return []string{
        "0", "1", "2", "3", "4", "5",
        "6", "7", "8", "9", "A", "B",
        "C", "D", "E", "F",
    }
}

func randElementFromMap(m *map[string]string) string {
    x := rand.Intn(len(*m))
    for k := range *m {
        if x == 0 {
            return k
        }
        x--
    }
    return "Error"
}

func getSHA1Hash(content []byte) string {
    h := sha1.New()
    h.Write(content)
    return base64.URLEncoding.EncodeToString(h.Sum(nil))
}