> On May 3, 2:13 pm, Anthony Williams yahoo.com> wrote:

>> Szabolcs Ferenczi gmail.com> writes:

>>> On May 2, 12:43 pm, Anthony Williams yahoo.com> wrote:

>>>> [...]
>>>> All accesses to shared data MUST be synchronized with atomics: [...]

>>

>>> Can you elaborate this point please. How can you generally synchronise
>>> N processes with help of atomics? Do you mean only two processes under
>>> certain circumstances?

>>
>> If any thread modifies shared data that is not of type atomic_xxx, the
>> developer must ensure appropriate synchronization with any other thread
>> that
>> accesses that shared data in order to avoid a data race (and the
>> undefined
>> behaviour that comes with that).

>
> It is clear that you must synchronise access to shared variable. ...

> On May 3, 2:13 pm, Anthony Williams yahoo.com> wrote:

>> Szabolcs Ferenczi gmail.com> writes:

>>> On May 2, 12:43 pm, Anthony Williams yahoo.com> wrote...

> [this is in response to msg #13688, which has not been processed yet... I
> made a mistake, here is correction...]
>
>
>

>> "Dmitriy V'jukov" gmail.com> wrote in message
>>news:c5199756-8669-419e-84e9-1de582eff02e@y38g2000hsy.googlegroups.com...
>> [...]

>>> I can prove that I have happens-before relation if I can enforce
>>> correct compiler ordering. Consider following code:

>

>>> std::vector g_nonatomic_user_data;
>>> std::atomic_int g_atomic1;
>>> std::atomic_int g_atomic2;

>

>>> std::vector thread()
>>> {
>>> g_atomic1.store(1, std::memory_order_relaxed);
>>> // compiler store-load fence ...

> "Szabolcs Ferenczi" gmail.com> wrote in message

> news:e97bdaf4-5f8a-40bd-b058-46b30b1eb01a@x35g2000hsb.googlegroups.com...

>> On May 3, 2:13 pm, Anthony Williams yahoo.com> wrote:

>>> Szabolcs Ferenczi gmail.com> writes:

>>>> On May 2, 12:43 pm, Anthony Williams yahoo.com> wrote:

>>>>> [...]
>>>>> All accesses to shared data MUST be synchronized with atomics: [...]

>>>> Can you elaborate this point please. How can you
>>>> generally synchronise N processes with help of atomics?
>>>> Do you mean only two processes under certain
>>>> circumstances?

>>> If any thread modifies shared data that is not of type
>>> atomic_xxx, the developer must ensure appropriate
>>> synchronization with any other thread that accesses that
>>> shared data in order to avoid a data race (and the
>>> undefined behaviour that comes with that).

>> It is clear that you must synchronise access to shared
>> variable. Normally you must use a Critical Region for that.

> Szabolcs Ferenczi gmail.com> writes:

>> On May 3, 2:13 pm, Anthony Williams yahoo.com> wrote:

>>> Szabolcs Ferenczi gmail.com> writes:

>>>> On May 2, 12:43 pm, Anthony Williams yahoo.com> wrote:

>>>>> [...]
>>>>> All accesses to shared data MUST be synchronized with atomics: [...]

>

>>>> Can you elaborate this point please. How can you generally synchronise
>>>> N processes with help of atomics? Do you mean only two processes under
>>>> certain circumstances?

>

>>> If any thread modifies shared data that is not of type atomic_xxx, the
>>> developer must ensure appropriate synchronization with any other thread that
>>> accesses that shared data in order to avoid a data race (and the undefined
>>> behaviour that comes with that).

>

>> It is clear that you must synchronise access to shared variable.
>> Normally you must use a Critical Region for that.

> ...