Why shouldn't I use Apache2 with a threaded MPM in a production environment?
PHP is glue. It is the glue used to build cool web applications by sticking dozens of 3rd-party libraries together and making it all appear as one coherent entity through an intuitive and easy to learn language interface. The flexibility and power of PHP relies on the stability and robustness of the underlying platform. It needs a working OS, a working web server and working 3rd-party libraries to glue together. When any of these stop working PHP needs ways to identify the problems and fix them quickly. When you make the underlying framework more complex by not having completely separate execution threads, completely separate memory segments and a strong sandbox for each request to play in, feet of clay are introduced into PHP's system.

If you feel you have to use a threaded MPM, look at a FastCGI configuration where PHP is running in its own memory space.

And finally, this warning against using a threaded MPM is not as strong for Windows systems because most libraries on that platform tend to be threadsafe.
 

...
Như vậy thì có nên sử dụng php với worker không? Theo mình biết thì worker là một dạng lai giữa process và thead nên nó có một số ưu điểm về mặt hiệu suất so với prefork và tất nhiên là mình muốn sử dụng worker. Nhưng trên thực tế thì đa số các gói binary đóng gói sẵn cho linux đều sử dụng prefork.

Mong các bạn có ý kiến về việc này 

# cat fastcgi.conf 
LoadModule fastcgi_module modules/mod_fastcgi.so
AddHandler php-fastcgi .php

<Location /cgi-bin/php-cgi>
       SetHandler fastcgi-script
</Location>

Action php-fastcgi /cgi-bin/php-cgi
DirectoryIndex index.html index.php
AddType application/x-httpd-php .php

<VirtualHost *:80>
	ServerName host.quanta.com
	ServerAdmin quanta@
	DocumentRoot /usr/local/apache2/htdocs	

	<Directory /usr/local/apache2/htdocs>
	        Options ExecCGI
	</Directory>
</VirtualHost>