Can I think the atomic store and load operation in go are equivalent to
the atomic load and store with *memory_order_relaxed* in c++?
On Sunday, October 22, 2017 at 12:12:19 PM UTC-4, T L wrote:
>
> And how about this one. Also no guarantees to always print 1?
>
> package main
>
> import "fmt"
> import "sync/atomic"
> import "runtime"
>
> func main() {
> runtime.GOMAXPROCS(1)
> var a, b int32 = 0, 0
>
> go func() {
> atomic.AddInt32(&a, 1)
> atomic.AddInt32(&b, 1)
> }()
>
> for {
> if n := atomic.LoadInt32(&b); n == 1 {
> fmt.Println(atomic.LoadInt32(&a)) // always print 1?
> break
> }
> runtime.Gosched()
> }
> }
>
> On Sunday, October 22, 2017 at 9:59:11 AM UTC-4, T L wrote:
>>
>> So the Go 1 memory model really make no guarantees that the following
>> program will print 1?
>>
>> package main
>>
>> import "fmt"
>> import "sync/atomic"
>> import "runtime"
>>
>> func main() {
>> runtime.GOMAXPROCS(1)
>> var a, b int32 = 0, 0
>>
>> go func() {
>> a = 1
>> atomic.AddInt32(&b, 1)
>> }()
>>
>> for {
>> if n := atomic.LoadInt32(&b); n == 1 {
>> fmt.Println(a) // always print 1?
>> break
>> }
>> runtime.Gosched()
>> }
>>
>> On Sunday, October 22, 2017 at 6:33:42 AM UTC-4, T L wrote:
>>>
>>>
>>>
>>> On Sunday, October 22, 2017 at 5:55:54 AM UTC-4, Jan Mercl wrote:
>>>>
>>>> On Sun, Oct 22, 2017 at 9:19 AM T L <tapi...@gmail.com> wrote:
>>>>
>>>> > why?
>>>>
>>>> The OP code with line numbes: https://play.golang.org/p/4fmiWqDDc1
>>>>
>>>> The main goroutine busy loops at lines 15-20. Because of that the
>>>> goroutine at line 10 may never run and thus line 17 may never get
>>>> executed.
>>>> If so, line 18 and thus also lines 27 and above may also never get
>>>> executed.
>>>>
>>>> --
>>>>
>>>> -j
>>>>
>>>
>>> Aha, yes, if GOMAXPROCS is 1, then the main goroutine will become greedy.
>>>
>>>
>>
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