Re: CreateThread / CRT

Mark Salsbery [MVP] wrote:


Very interesting read, but I think the author has it backward what a certain
compiler guarantees 'volatile' to do[1] and what the C or C++ standards
guarantee. Claiming that declaring even just a flag volatile was enough to
work in a multithreaded environment is definitely wrong, in the sense that
it relies on an implementation detail of a certain compiler (or maybe a
requirement of the win32 API), but that's the case with all multithreaded
programming anyway.

Further, the claim that accesses to an object guarded by a CRITICAL_SECTION
are unsafe if the object itself is not 'volatile' is plainly wrong. If this
was true it would mean that you couldn't use e.g. a CString safely, because
the volatile doesn't e.g. affect the internal types of that object.

Uli

[1] I'm reading the "Using PeekMessage anywhere" paragraph, particularly
referring to the phrase

 "The BOOL variable access is carefully synchronized, which is
  unnecessary, and it is not declared volatile, which is necessary."