Go Brain Teasers

Puzzle 8

Sleep Sort

sleep_sort.go

package main

import (
        "fmt"
        "sync"
        "time"
)

func main() {
        var wg sync.WaitGroup
        for _, n := range []int{3, 1, 2} {
                wg.Add(1)
                go func() {
                        defer wg.Done()
                        time.Sleep(time.Duration(n) * time.Millisecond)
                        fmt.Printf("%d ", n)
                }()
        }
        wg.Wait()
        fmt.Println()
}

Guess the Output
	Try to guess what the output is before moving to the next page.

This code will print: 2 2 2

You probably expected 1 2 3. Each goroutine sleeps n milliseconds and then prints n.