I don't know much about the technicalities of it, but CentOS 7 uses systemd which is running Apache inside a 'slice', this is unlike previous versions of CentOS which used the SysV init style where things more or less run in the root environment. As far as I understand, the idea is to offer each daemon a "clean" running environment where daemons won't interfere with eachother.

$ systemctl status httpd
httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)
   Active: active (running) since Thu 2014-12-04 08:13:07 CET; 2h 9min
+ ago
  Process: 16316 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, st
+atus=0/SUCCESS)
 Main PID: 16321 (/usr/sbin/httpd)
   Status: "Total requests: 3; Current requests/sec: 0; Current traffi
+c:   0 B/sec"
   CGroup: /system.slice/httpd.service
           +-16321 /usr/sbin/httpd -DFOREGROUND
           +-16326 /usr/sbin/httpd -DFOREGROUND
           +-16327 /usr/sbin/httpd -DFOREGROUND
           +-16328 /usr/sbin/httpd -DFOREGROUND
           +-16329 /usr/sbin/httpd -DFOREGROUND
           +-16330 /usr/sbin/httpd -DFOREGROUND
           +-16405 /usr/sbin/httpd -DFOREGROUND
[download]