同時実行 Go プログラムでアクティブな Goroutine を正確にカウントするにはどうすればよいですか?

import (
    "fmt"
    "sync"
)

var element int

func deen(wg *sync.WaitGroup, queue chan int) {
    for element := range queue {
        wg.Done() // Decrement the WaitGroup count upon completion
        fmt.Println("element is", element)
        if element%2 == 0 {
            fmt.Println("new element is", element)
            wg.Add(2) // Increment WaitGroup count for spawned goroutines
            queue <- (element*100 + 11)
            queue <- (element*100 + 33)
        }
    }
}

func main() {
    var wg sync.WaitGroup
    queue := make(chan int, 10)
    queue <- 1
    queue <- 2
    queue <- 3
    queue <- 0

    fmt.Println("initial active goroutines:", runtime.NumGoroutine())

    for i := 0; i < 4; i++ {
        wg.Add(1) // Increment WaitGroup count for each spawned goroutine
        go deen(&wg, queue)
    }

    wg.Wait() // Wait for all goroutines to complete
    close(queue)
    fmt.Println("final active goroutines:", runtime.NumGoroutine())
    fmt.Println("list length:", len(queue)) // Expect 0
}