From: Ned Konz <ned@...>
Date: 2001-11-02T09:46:25+09:00
Subject: [ruby-talk:24131] Re: cost of threads vs. continuations

On Thursday 01 November 2001 04:41 pm, Avi Bryant wrote:
> How different are the costs of a continuation and a suspended thread?  It
> seems like they ought to be almost identical, but is there anything in the
> internals that makes one preferable to the other?  Is it reasonable to
> have, say, a hundred or even a few hundred active threads or continuations
> at once?

I thought continuations were implemented using threads.

> I'm playing with extending iowa to allow web apps written in something
> like a continuation-passing style (normally, passing control to another
> page is much like a goto, and I want to allow something that looks like
> a subroutine call), and although the idea is most naturally expressed
> using call/cc it may be hackable with threads instead.  Of course, if
> continuations are cheaper, then I won't bother. ;-)

Another possibility might be to use futures (what Smalltalk often calls a 
Promise); this gives you reasonably transparent thread synchronization. With 
Ruby's join() method, it's easy to implement as well.

-- 
Ned Konz
currently: Stanwood, WA
email:     ned@bike-nomad.com
homepage:  http://bike-nomad.com