The problem happened when I could not start the Apache service when the production server was overloading.
root@servername [~]# service httpd start
(98)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
Unable to open logs
Lets run the netstat to check the Apache process is hook up with which other process.
root@servername [~]# netstat -lnp | grep ’0.0.0.0:80′
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 22666/exim
Next, run the ps command to check above listening process
root@servername [~]# ps 22666
PID TTY STAT TIME COMMAND
22666 ? S<s 0:00 /usr/sbin/exim -Mc 1L5ryZ-0005tZ-T0
GotYa. Is confirmed that Apache process could not stop due to Exim process.
Run the service reboot command to Exim service. Give a shoot by restarting Exim and then start Apache will wake up your Apache service.
Note : This is an example situation which it does not really relates to Exim process. It could be other process. Do check with netstat command and you will find out.