Re: C++ Threads, what's the status quo?

From:

"Mirek Fidler" <cxl@ntllib.org>

Newsgroups:

comp.lang.c++.moderated

Date:

7 Jan 2007 18:35:07 -0500

Message-ID:

<1168188975.880690.14790@38g2000cwa.googlegroups.com>

Le Chaud Lapin wrote:

James Kanze wrote:

Le Chaud Lapin wrote:

The point is that C++ and threading are alive and well. People use
them together. Some people use the native API of their OS, which is
not always pleasant to use. Some people wrap these API's.

The point is that you don't know that it works, and that it
works only by chance (and may actually fail once you start using
a multi-core processor). The point is that you don't have any
guarantees with regards to what the language or the compiler
provides.

I never asked the compiler for any guarantees. What did you study in
university? I do not mean to attack you personally, but frankly, these
concepts are as old as multi-threading itself. I am appalled that so
many people seem not to understand multi-threading.

Ahh... I guess you should seriously reconsider the issue.

Recommended reading is e.g. google: "why double checked guard does not
work".

Just for starters, if you have

Shared y;
Mutex y_lock;

void fn() {
   y_lock.Lock();
   y = 10;
   y_lock.Unlock();
}

nothing in C++ standard prevents C++ compiler to generate machine code
equivalent to

void fn() {
   y = 10;
   y_lock.Lock();
   y_lock.Unlock();
}

(and now I recommend you to get some C++ reeducation before your
threads start to fail with new compiler version ;)

Mirek

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