Demonstration of channel ordered receives

chan_order.go

package main

import (
	"fmt"
	"sync"
)

type element struct {
	Goroutine int
	Index     int
}

func main() {
	n := 10
	list := []element{}
	ch := make(chan int)
	var wg sync.WaitGroup
	var mu sync.Mutex
	wg.Add(n)

	for i := 1; i <= n; i++ {
		go func(i int) {
			mu.Lock()
			list = append(list, element{i, <-ch})
			mu.Unlock()
			wg.Done()
		}(i)
	}

	for i := 1; i <= 10; i++ {
		ch <- i
	}
	wg.Wait()

	for _, e := range list {
		fmt.Println(e.Index, "added by", e.Goroutine)
	}
}

sample_output.txt

# first run
1 added by 10
2 added by 1
3 added by 2
4 added by 3
5 added by 4
6 added by 5
7 added by 6
8 added by 7
9 added by 8
10 added by 9


# second run
1 added by 2
2 added by 8
3 added by 10
4 added by 4
5 added by 3
6 added by 7
7 added by 5
8 added by 1
9 added by 9
10 added by 6