[mikey_p]

With PHP 5.3.9 or 5.3.10 and php-fpm a new method of process management called ondemand was introduced that handles this use care very well. With a super short idle timeout (a few seconds) this could work very well for shared hosting, but I doubt there are many folks using it since it does still require the process manager to stay running in order to start the workers (this makes it hard to have user configurable php.ini settings since it would require restarting the master).

See http://www.php.net/manual/en/install.fpm.configuration.php under 'pool' group and the 'pm' setting.

[rmccue]

You can send a signal to php-fpm to reload configuration without restarting (at least, the way I read it). My /etc/init.d/php-fpm has "reload" with `kill -USR2 $PHP_PID`