Small and simple example demonstrating a race condition. Intended to introduce newcomers to the world of concurrency problems.

raceDemo.go

package main

import (
	"fmt"
	"sync"
)

func demoRace() {
	race := func() int {
		i := -1
		var wg sync.WaitGroup
		wg.Add(2)

		// Race contestant 1
		go func() {
			i = 0
			wg.Done()
		}()

		// Race contestant 2
		go func() {
			i = 1
			wg.Done()
		}()

		wg.Wait()
		return i
	}

	n := 1000
	cnts := []int{0, 0}
	for n > 0 {
		res := race()
		cnts[res]++
		n--
	}
	fmt.Println(cnts)
}

func main() {
	demoRace()
}