Change Apache MPM from Prefork to Worker

• By default Apache will use prefork MPM.
• you can verify it by executing httpd -l . 

[user@linuxbox ~]$ httpd -l

   Compiled in modules:

    core.c

    prefork.c

    http_core.c

    mod_so.c

• If you want to change it into worker MPM. Open the file 

     vi /etc/sysconfig/httpd

and uncomment the line 

      #HTTPD=/usr/sbin/httpd.worker

Then if you check again the command httpd -l you can still see prefork.c listed there. But that doesn't mean that Apache now using Prefork. It just mean that at the time when apache configured it was compiled with the option prefork. 

So how do you know which MPM apache is using?

Just check the Apache process using ps aux | grep httpd  or use top command

• httpd means Apache is running as prefork
• httpd.worker means it is running as worker