How is PHP script executed in apache

["Chidanand Gangur" <chidanand.gangur@xxxxxxxxx>]

Hi,

I have compiled PHP as module in apache. Recently I have noticed a strange problem when apache executes the PHP script.

My assumption till date:

1. If there are number of request destined to the same/different PHP
page then apache will spwan child process to handle the load.
2. If two requests are sent simultaneously on same page then apache
module will process those two requests parallely with two different
child threads.

Am I right on my assumptions? 

1. In my test I have x.php which talks to a backend modules
2. I send some request to x.php which inturn lands on the backend module(1) through sockets.
3. Mean while when backend module(1) is busy in processing, another request arrives on the x.php.
4. This request  is destined to backend module (2)

My observation here is the response from the backend module( 2) is
blocked till the response from backend module( 1) is completed.
whereas as per my assumption apache shoud have processed these two
requests in two different threads/child process without blocking.

Is this expected behaviour? what should I do to get parallelism.
I would like to know more about how the php scripts are processed in apache, can some one guid me to a useful link.

--
Thanks, 
Chidanand Gangur
Pune.