Apache monitoring

[marco di sano <marcodisano@xxxxxxxxx>]

Hi all,
I'm new in this group.
I ask you if it is possible to 
monitoring the function calls that Apache makes when it must satisfy a 
request. For example, suppose we have a LAMP architecture (this is my 
architecture) and I want to display all the users in a database table (it
 exists). Is it possible to trace all the call functions that Apache 
makes to achieve this goal?I am not interested to log errors, but the 
call functions that belong to the apache library.
I want to know what are the function libraries that Apache calls when it serves an http request(for example).
I tried to use strace but it traces the Unix system calls and not the 
php functions that Apache does when a request must to be served.

Somebody help me!

Thanks