From: Eric Hodel <drbrain@...7.net>
Date: 2007-08-14T12:30:13+09:00
Subject: Re: Why don't Ruby libraries share memory?

On Aug 13, 2007, at 11:25, Matt Harvey wrote:
> This paragraph is motivation. While my question is not Rails- 
> specific, I am asking it because of Rails. I've been investigating  
> the memory footprint of my Mongrels. It is nice that they share  
> the .so libraries from ImageMagick as well as other C libraries.  
> However, each one still has about 20MB in [heap]. My theory is that  
> a lot of this is coming from ActiveRecord and friends getting  
> loaded again and again for each Mongrel, which seems to me entirely  
> unnecessary. My "marginal cost of Apache" is 1376kB. My "marginal  
> cost of Mongrel" is 27528kB, with the code I wrote. It seems that  
> the latter could be reduced a lot by sharing some Ruby libraries.
>
> The question is as follows: if I require 'library' in one instance  
> of Ruby and then require 'library' again in another instance of  
> Ruby, then do I get duplicate copies of library's code in two  
> chunks of my RAM? (I'm thinking I do.) Why?

You'll get closer to the behavior you expect if you use Kernel#fork  
to spawn new instances rather than starting up from the shell.

This is how Apache costs only 1376kB.

--
Poor workers blame their tools. Good workers build better tools. The
best workers get their tools to do the work for them. -- Syndicate Wars