From: Mark Hahn <mchahn@...>
Date: 2001-12-20T09:01:37+09:00
Subject: [ruby-talk:29038] Re: A Ruby programmer walked into a bar and ordered a Ruby-Thread


I don't understand the problem.  I just ran this on windows:

Thread.new {loop{print 'a';sleep(0.1)}}
Thread.new {loop{print 'b';sleep(0.214)}}
sleep(2)

	==> abaabaabaabaabaabaabaabaaabaab

If you are talking about two greedy threads that both ask for 100% of the
cpu, then that is bad coding and the result is unpredictable.  This is true
in any threading environment.

Now processes are a different matter.  They are supposed to be pre-emptive
and asking for 100% of the cpu is perfectly ok.

-----Original Message-----
From: HarryO [mailto:harryo@zipworld.com.au]
Sent: Wednesday, December 19, 2001 3:28 PM
To: ruby-talk ML; undisclosed-recipients:
Subject: [ruby-talk:29036] Re: A Ruby programmer walked into a bar and
ordered a Ruby-Thread


On Thu, 20 Dec 2001 07:58:47 +1100, Dave Thomas wrote:

> Well, not really. Under Windows, there doesn't seem to be any switching
> between threads in some circumstances. Each thread runs to completion,
> and then another starts. Although arguably correct in a theoretical
> sense, it isn't much use in practice. Under Unix, threads play nicely
> with each other (hence the example with counters in the book).

In which case, the concept that the threading is done in the interpreter
to make it OS independent seems a little "dodgey" for want of a
better word.  There's not a lot of point having threads if they don't
effectively run in parallel.

Maybe there needs to be more emphasis on this made in documentation
somewhere ... maybe it is and I just haven't seen it because I'm
not overly interested in Windows.

Obviously, Ruby is still a wonderful thing to have, even on Windows,
but if one specifically wanted to do multithreading, it would be a
little annoying to go to the effort, only to discover that it
didn't work as you'd expect threading to work .. ie, in a natural,
straightforward way.

> The interpreter is not thread safe, and the consensus seems to be that
> making it so would be a waste of time, given the upcoming rewrite. A
> secondary issue is the extensions that are already out there. How many
> of there are also not thread safe, and what impact would running under a
> native threading model have on them?

Yes, I guess when 2.0 comes out, this will all become a non-issue, so
as a Linux user, I'll content myself with being sympathetic towards
the Windows Ruby-ists until then :-).