Subj : Re: Can C++ local static objects be made thread safe?
To   : comp.programming.threads
From : Marcin 'Qrczak' Kowalczyk
Date : Wed Jan 19 2005 01:37 am

Olivier Huet <huet-pasdespamsvp-.o@caramail.com> writes:

>> Depending on whether the variable is process wide or system wide.
>
> Yes, but generally, the compiler itself doesn't know it : in a lot of
> couples compiler+OS, variables are done "system wide" with some OS
> calls : shared memory, memory file mapping etc.

On Unix a static variable in a function cannot be system wide. You can
obtain shared memory or mmap region first, and then put objects at the
address you got. This can't apply to static variables whose address is
predetermined by the compiler.

I think on Windows you can choose whether a DLL will have its memory
shared between processes or not. Determining the kind of lock should
be delayed until the scope of the DLL is determined. I don't know if
this is implementable.

-- 
   __("<         Marcin Kowalczyk
   \__/       qrczak@knm.org.pl
    ^^     http://qrnik.knm.org.pl/~qrczak/

.