Test if Go's assignment is atomic

atomic-assignment-test.go

package main

import (
	"fmt"
	"runtime"
)

func main() {
	var (
		k string // do assignment and read to this variable
		i = "hello"
		j = "world there"
	)

	runtime.GOMAXPROCS(2)

	done := false

	go func() {
		// assign k, see if this is atomic
		for !done {
			k = i
			k = j
		}
	}()

	// repeatedly read k
	// if assignment is atomic, this loop will never end
	// real world results:
	// 1. crash: invalid memory address or nil pointer dereference
	// 2. print "hello"
	// 3. print "world"
	for {
		p := k
		if p != "" && p != i && p != j { // crash on this line
			fmt.Println(p)
			done = true
			break
		}
	}
	return
}