Race condition example in stingy_spendy does not work

[osadasami]

I use golang 1.17. And this code 8e48ac5638a972ffd4b003b88379949e691edbe8 to simulate race condition.

For each run I always get 100 but there should be different numbers.

What might be wrong? Don't we need locking anymore?

[cutajarj]

Hi, You always need synchronization mechanisms, whatever language you are using. This is the same in go lang 1.17. I tried running your code using 1.17 and I manage to reproduce a race condition by increasing the loop count and removing the sleep. This is to increase the chances of the race condition happening:

package main

import "time"

var (
	money = 100
)

func stingy() {
	for i := 1; i <= 100000; i++ {
		money += 10
		//time.Sleep(1 * time.Millisecond)
	}
	println("Stingy Done")
}

func spendy() {
	for i := 1; i <= 100000; i++ {
		money -= 10
		//time.Sleep(1 * time.Millisecond)
	}
	println("Spendy Done")
}

func main() {
	go stingy()
	go spendy()
	time.Sleep(2000 * time.Millisecond)
	print(money)
}

When I run it I get:

go run sync\stingy_spendy.go
Stingy Done
Spendy Done
-517960

[osadasami]

Thank you, now the simulation is working.