Get number of currently running/active goroutines

NumGoroutine function of runtime package can be used to know the currently running/active goroutines.

https://golang.org/pkg/runtime/#NumGoroutine

Below is the signature of the function

func NumGoroutine() int

Working Code:

package main

import (
    "fmt"
    "runtime"
    "time"
)

func main() {
    for i := 0; i < 20; i++ {
        go execute()
    }
    fmt.Println(runtime.NumGoroutine())
}

func execute() {
    time.Sleep(time.Second * 10)
}

Output:

21