Go And Weak Memory Ordering

a.go

package main

import (
	"log"
	"math/rand"
)

//import "runtime"

var x, y, r1, r2 int
var ch1 = make(chan int)
var ch2 = make(chan int)

func run1() {
	for {
		<-ch1
		for {
			if rand.Int31()%8 == 0 {
				break
			}
		}
		x = 1
		r1 = y
		ch1 <- 1
	}
}
func run2() {
	for {
		<-ch2
		for {
			if rand.Int31()%8 == 0 {
				break
			}
		}
		y = 1
		r2 = x
		ch2 <- 1
	}
}

func main() {
	go run1()
	go run2()

	detected := 0

	for i := 1; ; i++ {
		x = 0
		y = 0
		ch1 <- 1
		ch2 <- 1

		<-ch1
		<-ch2

		if r1 == 0 && r2 == 0 {
			detected++
			log.Printf("%d reordered detected, runc: %d", detected, i)
		}
	}
}

/*

# ./a
2021/06/28 02:02:35 1 reordered detected, runc: 8507500
2021/06/28 02:02:35 2 reordered detected, runc: 8523412

*/