I think some of us have an interest in implementing reaps. However, I'm not going to touch the pools code to get another mechanism in place anytime soon. I know apr_free can be added to the current code with little trouble, keeping the costs in the free.
I didn't mean to touch the existing pool. I thought it might be interesting to have an additional kind of pool so that the user has some more choice.
In any case I think it would be nice to see your code ;)
http://www.php.net/~andi/zend_mm/
Andi
