From: Rick DeNatale <rick.denatale@...>
Date: 2006-10-06T01:16:35+09:00
Subject: Re: Timeout and Exponetial Regexes

On 10/5/06, eden <eden.li@gmail.com> wrote:

> However, the point of my post is not the regex.  What I was trying to
> find out was why Ruby seems to block threads whenever a regex is
> running.

I'm not entirely sure, but I suspect that it's because of the use of
green threads, rather than native threads.

Native threads can get scheduled whenever there's a hardware interrupt.

Thread switching for green threads only happens when certain internal
functions are called e.g. rb_thread_schedule.  I suspect that the
regex engine isn't calling this, or if it does it doesn't call it very
often.

If this is the case it's not really blocking threads explicitly, but
the effect is the same.

Just a theory, I haven't slogged through the code thoroughly enough to prove it.

-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/