I was disturbed by a question,
should we add lock if only one thread write variable, and other thread just read variable?
so I write such code to test it
package main
import (
"fmt"
"runtime"
"sync"
"time"
)
var lock sync.RWMutex
var i = 0
func main() {
runtime.GOMAXPROCS(2)
go func() {
for {
fmt.Println("i am here", i)
time.Sleep(time.Second)
}
}()
for {
i += 1
}
}
The result is keep print i am here 0
even after second of time. I know a little about Memory barrier or cpu cache. but how could it be cache for such a long time? I think after a few time, it should read variable I already changed.
Can anyone who is master go or computer system could help answer, please?
Update: i know it is a wrong way to update variable like this, i want to know why it is undefined in cpu/memory view.
finally, i find this answers, i know with a data race you will get a undefined behave, but i want to know why it behave like that currently.
this snap code is because complier just remove Add function, it never add.
so we have lesson, if you write a undefined behave, you may got a moon - -
complier will treat you code as rubbish, it does not have any value.