From: khaines@...
Date: 2007-10-10T00:50:45+09:00
Subject: Re: thread problem.....

On Tue, 9 Oct 2007, Michael Bevilacqua-Linn wrote:

> 1.) The only way threads get you a speedup is when you write your code in
> such a way that sections of it can be executed in parallel so you can take
> advantage of multiple cores (or processors).
>
> 2.) The current version of Ruby only supports green threads anyhow.  So even
> if you did have multiple cores, you wouldn't get a speedup.

It's not that simple.  With Ruby's green threads, it all depends on 
whether there's a latency somewhere, in one thread, that can allow another 
to make use of that time and get something done.

You aren't going to find that latency in any CPU bound operation, and you 
aren't going to find that latency in any extension to Ruby that was not 
written to be Ruby aware.

If your problem is IO bound, though, ruby can capture that time where one 
thread is waiting on IO to let another thtread do something.  In those 
cases, you can get a speedup from Ruby's green threads.


Kirk Haines