Re: Am I or Alexandrescu wrong about singletons?
On Mar 20, 7:13 am, red floyd <redfl...@gmail.com> wrote:
On Mar 19, 2:06 am, "Leigh Johnston" <le...@i42.co.uk> wrote:
That was my point, volatile whilst not a solution in itself
is a "part" of a solution for multi-threaded programming
when using a C++ (current standard) optimizing compiler:
thread A:
finished = false;
spawn_thread_B();
while(!finished)
{
/* do work */
}
thread B:
/* do work */
finished = true;
If finished is not volatile and compiler optimizations are
enabled thread A may loop forever.
Agreed. I've seen this in non-threaded code with
memory-mapped I/O.
Which is a different issue. That's what volatile was designed
for: I think it still works for that on Intel architecture. (It
doesn't on Sparc, at least with g++ or Sun CC:-(.) Threading is
a different issue.
Note that volatile is still relevant for communications between
a signal handler and the main (single threaded) application. At
least according to the standard.
--
James Kanze
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