Understanding WaitGroup in Go (Golang)

WaitGroup is a struct that is part of sync package in Go. It is generally used to wait for a collection of goroutines to finish execution. The WaitGroup has below methods

• Add method to set the number of goroutines to wait for.

• Done method which is called by each of the goroutines when finished.

• Wait method which is used to block till all goroutines have finished and have called the Done method

Let’s see a working code:

package main
import (
"fmt"
"sync"
"time"
)
func main() {
var wg sync.WaitGroup
wg.Add(2)
go sleep(&wg, time.Second*1)
go sleep(&wg, time.Second*2)
wg.Wait()
fmt.Println("All goroutines finished")
}
func sleep(wg *sync.WaitGroup, t time.Duration) {
defer wg.Done()
time.Sleep(t)
fmt.Println("Finished Execution")
}

Output:

Finished Execution
Finished Execution
All goroutines finished