From: Sam Roberts <vieuxtech@...>
Date: 2008-07-03T14:18:01+09:00
Subject: Re: Threads and Ruby

On Tue, Jul 1, 2008 at 1:31 PM, Charles Oliver Nutter
<charles.nutter@sun.com> wrote:
> Of course that's mostly a factor of Ruby's rather simplistic thread
> scheduling, which has a 10ms timeslice and a fairly basic selection
> algorithm. Obviously OS scheduling will be better/more advanced, but that
> applies equally well to native threads (like in JRuby).

Reminds me of the last time I looked at ruby's thread scheduling,
every wakeup from select() caused a traversal of the entire list of
threads to see if any were blocked on #sleep(). This has horrid
performance characteristics for large numbers of threads doing
periodic actions.

Rewriting code to be single-threaded, and keeping a priority queue of
waiting actions solved my apps performance problem, but also made the
point that the OS works very hard to have good scheduling behaviour
for threads under wide usage patterns, whereas ruby's scheduler just
gets the job done.

Cheers,
Sam