Ok. ikegami made a correct statement about cond_wait in which the lock is re-obtained before cond_wait returns. This is documented in the threads::shared documentation. Ikegami did not lie.

I ran your demonstration with the lock outside the while loop. The $cnt variable in the printer routine is for having the script exit at some point.

ikegami made a correct statement about cond_wait in which the lock is re-obtained before cond_wait returns. This is documented in the threads::shared documentation.

All well and good, except that no one, least of all me, has been arguing about that. A correct statement about something that was never in question; doesn't change anything.

Ikegami did not lie.

Sorry, but Ikegami saying: "For me, it works fine in Windows too." -- when he must have known, (and later acknowledges as much), that his code hangs on windows -- is disingenuous.

I ran your demonstration with the lock outside the while loop.

It is not "my demonstration" if the lock() is outside the loop. THAT'S THE "£$%^*#@ POINT! (Or at least one of them.)

Now, give it up.

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority". I knew I was on the right track :)

In the absence of evidence, opinion is indistinguishable from prejudice.

he must have known, ... that his code hangs on windows

But, you have said it yourself, in here,

emulated cond_vars can be used on Windows; but doing so successfully requires an understanding of their inherent limitations (which exist everywhere, but are exacerbated by the crude emulation on Windows)

and here,

The best I've been able to conclude is that the signal is simply not seen by the waiters; because of the crude and sloppy emulation.

... and yet you chose to make use of said emulation, with due care and diligence as it would seem.

Lesser men tend to be lacking in such deep insight, that apparent requirement in writing exemplary threaded code. Please be understanding with us!

Would it be possible to share this knowledge, to outline the guiding principles and design considerations, so as to allow us to build robust, working solutions ourselves, all the while avoiding the dangerous pitfalls, taboos and uncertainties? Much obliged!

Shame on ikegami. I now understand your frustration and the reason for the attacks.

The following resolves the printer output having two zeros. That led to the confusion. It looks like somebody already mentioned it.

   $a = int(rand() * 100) + 1;
[download]

The OP presented an interesting problem. Seeing the double zeros led me on a wrong path. Please, for future monks testing your solution, can you kindly add + 1 inside set_positive.

sub set_positive {
    lock $a;
    while (1) {
        if ($a == 0) {
            $a = int(rand() * 100) + 1;
            $q->enqueue($a);
            print "At set_positive: $a\n";
        } else {
            cond_wait($a)
        }
        cond_broadcast($a);
    }
}
[download]

Thank you.