The benefit is simple -- you don't have to share memory. And that is
the *only* benefit to prohibiting the use of other synchronization
mechanisms.

Exactly

and that is the one benefit I am talking about. It allows
massive parallelisation of code, which is an enourmous benefit. That
benefit can be utilised when computers move to more and more cores per
processors, instead of the old game that was about more and more
kilo/mega/giga hertz.

It would help if you showed some indication that you understood what I
was saying.

This is a serious misunderstanding on your part. They *do* need to
share it and lock it. The reason for the message passing is precisely
to allow the threads to easily share and lock data.

But I appreciate your attempt at catching me in a minor "gotcha" so as
to waste time and avoid the major issues.

On Oct 9, 2:03 am, David Schwartz <dav... at (no spam) webmaster.com> wrote:

But I appreciate your attempt at catching me in a minor "gotcha" so as
to waste time and avoid the major issues.

I apologize for this comment. It was unwarranted.

On Oct 9, 12:11 am, Jan Helgesen <s... at (no spam) nospam.com> wrote:

The benefit is simple -- you don't have to share memory. And that is
the *only* benefit to prohibiting the use of other synchronization
mechanisms.

Exactly :)

So why are you asking about threads which do have to share memory?

That is a *cost* that only makes sense to pay if there's some
corresponding *benefit*.

Now imagine we switch collections A and B to a lock-free algorithm.
Now, there's a 50 percent chance that one thread will be A1 or A2 and
the other will be B1 or B2. In this case, there will be frequent
contention and the shared collection will constantly ping-pong from
cache to cache. FOR NO REASON.

It is with these advances in technology, I base my arguments. Since the
people working on these algorithms are acknowledged experts on the
matter of concurrency, I trust them a bit more than your unsupported
claims. Since you have not been able to convince me with your arguments,
  nor have you been able to produce any references that supports your
claim, I have little incentive to agree with you.

you have seen one of my references, maybe you could explain why you
think that is irrelevant.

David Schwartz wrote:
On Oct 12, 3:09 am, Jan Helgesen <s... at (no spam) nospam.com> wrote:

you have seen one of my references, maybe you could explain why you
think that is irrelevant.

That it is possible to do something right does not refute an argument
that it is possible to do something wrong. If you look at my last
paragraph of the post you didn't respond to, I explained that.

So your argument is: just because it is possible that something can go
wrong with anything, nothing is worth looking at? That's the most silly
rationale I have ever heard. The reference I showed you, shows that it
is possible to do it with 750 cpus. I have never claimed it works for 1
million cores yet, I have said that the future might be bright.

But this is a waste of time. You actively refuse to think and I'm
through trying. (I see no evidence you even attempted to understand my
argument.)

Arrgh, wtf is wrong with you. I have answered all your questions or
arguments that I find relevant. I have tried as hard as I can understand
how you get to your conclusions and how it is related to the case. But
every time I ask you to explain, you just change the examples you use or
the focus of your arguments, it is impossible to keep track of how all
your arguments are related and how it is relevant.

Your only response is to say generic and silly statements like "you show
no evidence... " or "you do not understand what I say.." and so on
without explaining explicitly what it is in my arguments you think are
are wrong.

You don't make arguments. You just say that I'm wrong and then cite
things that are either irrelevant or that actually agree with me. Can
you show some sign, any sign, that you understood my example about the
lock-free collections, the four threads, and the two cores?

On Oct 12, 2:27 am, Jan Helgesen <s... at (no spam) nospam.com> wrote:

It is with these advances in technology, I base my arguments. Since the
people working on these algorithms are acknowledged experts on the
matter of concurrency, I trust them a bit more than your unsupported
claims. Since you have not been able to convince me with your arguments,
nor have you been able to produce any references that supports your
claim, I have little incentive to agree with you.

I cannot convince you with my arguments because you are beyond
rational persuasion. I notice that you don't point out any errors or
flaws of any kind, you simply point to something completely irrelevant
and claim that it somehow refutes my argument when, ironically, it
actually supports it.

In any event, continue doing what you're doing having no understanding
of any of the concepts involved. I have exhausted my patience trying
to educate you.

DS

On Oct 12, 3:09 am, Jan Helgesen <s... at (no spam) nospam.com> wrote:

you have seen one of my references, maybe you could explain why you
think that is irrelevant.

That it is possible to do something right does not refute an argument
that it is possible to do something wrong. If you look at my last
paragraph of the post you didn't respond to, I explained that.

But this is a waste of time. You actively refuse to think and I'm
through trying. (I see no evidence you even attempted to understand my
argument.)

On Oct 11, 9:22 pm, David Schwartz <dav... at (no spam) webmaster.com> wrote:

Now imagine we switch collections A and B to a lock-free algorithm.
Now, there's a 50 percent chance that one thread will be A1 or A2 and
the other will be B1 or B2. In this case, there will be frequent
contention and the shared collection will constantly ping-pong from
cache to cache. FOR NO REASON.

Grr. Of course, this should read "that one thread will be A1 and the
other will be A2, or one thread will be B1 and the other will be B2".
In either case, for no reason at all, two threads are horribly
contending and saturating the FSB. Worse, if you have more than two
cores running threads from other processes, those threads can't make
decent forward progress because the FSB is saturated.

(My terminology assumes there *is* an FSB. But the issues are similar,
though not always precisely the same or as bad, if you have some other
technology.)

You don't make arguments. You just say that I'm wrong and then cite
things that are either irrelevant or that actually agree with me Can
you show some sign, any sign, that you understood my example about the
lock-free collections, the four threads, and the two cores?