package main

import (
	"fmt"
	"net"
	"sync"
)

func main() {
	const n = 300
	var wg sync.WaitGroup
	wg.Add(n)
	for i := 0; i < n; i++ {
		go func() {
			_, err := net.LookupHost("www.google.com")
			if err != nil {
				fmt.Println("error", err)
			}
			wg.Done()
		}()
	}
	wg.Wait()
}