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RE: Optimization of conditional access to globals: thread-unsafe?
On 28 October 2007 17:39, Erik Trulsson wrote:
> On Sun, Oct 28, 2007 at 01:10:00PM -0400, Robert Dewar wrote:
>> Erik Trulsson wrote:
>>
>>> Unfortunately it seems that the POSIX standard for threads say that as
>>> long as access to a shared variable is protected by a mutex there is no
>>> need to use 'volatile'.
>>
>> How does it say this, in some semantically precise way, or with hand
>> waving as in this sentence.
>
> I don't know. I don't have access to the POSIX standard itself so I have
> to depend on other peoples description of what POSIX says. (Thus my use of
> 'seems' above.)
> Everything I have found seem to agree that POSIX does not require the use of
> volatile though.
As far as I know, there is no separate 'pthreads' spec apart from what is
defined in the Threads section (2.9) of the SUS (http://tinyurl.com/2wdq2u)
and what it says about the various pthread_ functions in the system interfaces
(http://tinyurl.com/2r7c5k) chapter. None of that, as far as I have been able
to determine, makes any kind of claims about access to shared state or the use
of volatile.
cheers,
DaveK
--
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