On Monday, July 10, 2017 at 8:36:54 PM UTC+8, Jan Mercl wrote:
>
> On Mon, Jul 10, 2017 at 2:24 PM T L <tapi...@gmail.com <javascript:>>
> wrote:
>
> > Aha, what I wanted to express is the execution orders of the two lines
> may be randomized.
> >
> > atomic.AddInt32(&x, 1)
> > atomic.AddInt32(&y, 1)
>
> No, assuming those two lines are as written, ie. part of single function
> and thus executed in a single/the same goroutine. Then the memory model
> guarantees they are executed in order, ie. x will be updated before y. But
> there's no such guarantee when the same variable x and y are observed in a
> different, concurrently executing goroutine. To establish such ordering you
> have to synchronize, only that gives you the H-B relation within the
> synchronization participants.
>
> --
>
> -j
>
so this is guaranteed by go memory model?
package main
import "fmt"
import "sync/atomic"
func main() {
var x, y int32
atomic.AddInt32(&x, 1)
atomic.AddInt32(&y, 1)
if atomic.LoadInt32(&y) == 1 {
fmt.Println("x =", atomic.LoadInt32(&x)) // always 1 if it is
printed?
}
}
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