Finite Hate Machine

On Thursday, commenter Grumqa asked how PHP deals with the slow accumulation of functions if you call create_function.

It doesn’t.

<?php
for ($i = 0; $i < 100000; $i++)
    create_function("", "return 0;");
?>

This script fairly reliably kills the interpreter with the message “Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 40 bytes) …”. You can postpone it by increasing PHP’s memory limit, but if you call create_function an arbitrary number of times, eventually you will murder the interpreter. The only safe way to use create_function is by ensuring you only call it a bounded number of times, and at that point, why not use a normal function and be done with it?

Naturally, the PHP team doesn’t think this is a problem.

This entry was posted on Saturday, January 16th, 2010 at 4:00 pm and is filed under Ugly Implementation. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.