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Date: Mon, 05 Mar 2007 15:00:36 -0800
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Subject: Re: [PHP-DEV] The way the engine works?
From: rasmus@lerdorf.com (Rasmus Lerdorf)

Brian Moon wrote:
> Antony Dovgal wrote:
>> Yup, the language stole ~32Kb of your memory and used it to speedup
>> the allocation of small chunks.
> 
> Ok, in my attempt to send a sane looking example, I cleaned up the problem.
> 
> <?php
> 
> $str = "This is a medium length string";
> 
> $start = memory_get_usage();
> for($x=1;$x<=1000000;$x++){
>      $var = $str." ".$x.": (3.5): ".time()."\n";
> }
> $first_growth = number_format(memory_get_usage() - $start);
> 
> $start = memory_get_usage();
> for($x=1;$x<=1000000;$x++){
>      $var = "$str $x: (3.5): ".time()."\n";
> }
> $growth = number_format(memory_get_usage() - $start);
> 
> 
> echo "first growth: $first_growth\nsecond growth: $growth\n";
> 
> ?>
> 
> The introduction of $x into the string makes the difference.
> 
> first growth: 892
> second growth: 3,955,068

I get:

first growth: 704
second growth: 32,264

with current PHP_5_2 checkout.  I don't have a 5.1.x handy with memory
limits compiled in.

-Rasmus