An example how to use waitgroup in go.

waitgroup.go

package main

import (
	"fmt"
	"sync"
)

type Foo struct {
	ID int
}

type Result struct {
	Foo
	Message string
}

func main() {
	fmt.Println("Hello, playground")
	var wg sync.WaitGroup

	foos := []Foo{
		Foo{0},
		Foo{1},
		Foo{2},
		Foo{3},
		Foo{4},
		Foo{5},
	}

	results := make([]Result, len(foos))

	for i := range foos {
		wg.Add(1)
		go func(foo Foo, wg *sync.WaitGroup, results []Result) {
			fmt.Printf("ID: %v started\n", foo.ID)
			results[foo.ID].Foo = foo
			results[foo.ID].Message = fmt.Sprintf("The result is created for ID: %v", foo.ID)
			wg.Done()
		}(foos[i], &wg, results)

	}

	wg.Wait()

	fmt.Printf("Done, results: %+v", results)
}