Re: Only reading of variable vs. thread synchronisation

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 6 Jun 2008 03:09:44 -0700 (PDT)

Message-ID:

<e39b08fb-4b1c-46df-b48b-6e02f1ce97a7@k37g2000hsf.googlegroups.com>

On Jun 6, 11:14 am, "Hapa" <H...@apah.org> wrote:

This variable is using something like global memory. This
memory is written by a third party app, which takes care that,
we have no collision between two apps. But now I have two or
more threads whitin my app, which will only read this global
memory.

Which still isn't too clear: by global memory, do you mean
shared memory, with the third party application in a separate
process? And when you say that there is no collision between
the applications, do you mean that there will never be two
processes accessing this shared memory at the same time? If
your process has exclusive access to this shared memory, there
is no need for any synchronization between threads within the
process; all the memory synchronization you need has occured
when you acquired access to the shared memory. (At least under
Posix; I'll less sure about Windows.)

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