PHP Markdown, speed, MovableType (was "Michel Fortin")

[Michael Tsai]

On Dec 7, 2004, at 12:35 PM, John Gruber wrote:

> I'm fairly certain that PHP does no such caching. Each time you call
> preg_replace(), you're starting from scratch again.

Looking at the PHP source (both 4.3.8 and 5.0.2) it seems that it does 
cache compiled patterns.

Also, I wrote a little PHP program:

require "markdown.php";
$s = "...long string of Markdown text...";
while (true) {
     Markdown($s);
}

and ran Sampler on it. (You have to compile PHP yourself to do this; 
otherwise Sampler won't have access to debugging symbols.) The result 
is that 50x more time is spent in PCRE's "match" function than anywhere 
else, and almost no time is spent in "pcre_get_compiled_regex." PCRE 
just isn't as fast as Perl, although perhaps it's possible to tune the 
patterns to make them match faster.

> Python, on the other hand, allows the programmer to optionally
> control the compilation of patterns before using them:

Also, it automatically caches a fixed number of compiled regexes, even 
if you don't use re.compile.

--Michael