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Date: Sat, 21 Feb 2009 21:54:30 -0800
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To: shire <shire@tekrat.com>
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Subject: Re: [PHP-DEV] [RFC] APC/PHP Lazy Loading
From: ron@Opus1.COM (Ronald Chmara)

On Feb 21, 2009, at 4:10 PM, shire wrote:
> I've just checked into APC CVS preliminary support for Lazy Loading  
> classes and functions.  This means that rather than copying  
> function entries into EG(function_table) and EG(class_table) when  
> an include happen it will mark the functions/classes as available  
> and only actually insert them into the tables when they are called.

Wait... so if I understand this right, let's envision a code base  
where, per some random page load, 70 functions are actually called,  
but, oh, 7,000, or even 700,000, are being included for whatever reason?

The speed optimization is in *not* copying a massive amount of things  
that weren't even needed, or used, in the first place?

However, there's still the horribly massive speed hit of semi- 
loading, and marking, a fairly large amount of unused, un-needed,  
functions, as available?

While I do see, and understand, the performance benefit of such a  
coding direction, it's not exactly encouraging well designed code.

For example:
<?php
include(mega-loader.php);
//which kicks off
->include(site-mega-loader.php);
//which kicks off
-->include(sub-site-mega-loader.php);
//which kicks off
--->include(sub-site-application-loader.php);
//which kicks off
---->include(sub-site-application-feature-loader.php);
//which kicks off
----->include(sub-site-application-function-loader.php);
//which kicks off
------>include(sub-site-application-function-loader-function.php);

//and the actual code which caused the load?
my_custom_site_application_echo( "Hello World");

?>

This.... does not make me happy as a coder.

I do see the benefit of lazy loading, I'm just not very comfortable  
with enabling a philosophy of loading up a massive amount of CPU and  
RAM with "just in case they're wanted" features and code in the first  
place.

It *should* hurt to load something.

Code should not be ever loaded unless needed.

It certainly can boost an APC code set such as facebook, where many  
of those files and functions *will* likely be used in the next 20  
minutes or so, but I also fear that it will encourage programmers to  
load everything they have, every time, just in case they need it....  
and 2Gb apache processes (and APC space) can be.... ugly.

That being said, I think the idea is good, but the possible mis-uses  
are potentially tough issues.

-Bop