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Go Golang Different Ways to Wait for All Goroutines to Finish Execution
sync.WaitGroup
make(chan int, 5)
time.Sleep
//program: use of sync package’s WaitGroup structure
//Wait for All Goroutines to Finish
package main

import (
"fmt"
"sync"
)

func sum(list []int, wgp *sync.WaitGroup) {
sum := 0
for _, v := range list {
sum += v
}

fmt.Println("==In sum func==", sum)

wgp.Done()
}

func main() {
list1 := []int{2, 4, 6}
list2 := []int{1, 3, 7, 11}

var wg sync.WaitGroup
wg.Add(2)

go sum(list1, &wg)
go sum(list2, &wg)

wg.Wait()

}

//Go program ends when the main function ends.
//So goroutine doesn't get time to run and print its output.
//main() func need to wait for our goroutines to finish.

//A WaitGroup waits for a collection of goroutines to finish.
//The main goroutine calls Add to set the number of goroutines to wait for.
//Then each of the goroutines runs and calls Done when finished.
//At the same time, Wait can be used to block until all goroutines have finished.