Change Apache MPM on CentOS 7

Here’s an article on how to change your current Apache MPM on CentOS 7 machine. Apache version I’m using is Apache 2.4.

To check which MPM is currently in use you can run:

httpd -V

which should print something like:

...
Architecture:   64-bit
Server MPM:     prefork
  threaded:     yes (fixed thread count)
    forked:     yes (variable process count)
Server compiled with....
...

Default MPM worker should be prefork. If you want to change that, to let’s say, worker MPM you can do that by changing the file located in /etc/httpd/conf.modules.d named 00-mpm.conf which contains:

# Select the MPM module which should be used by uncommenting exactly
# one of the following LoadModule lines:

# prefork MPM: Implements a non-threaded, pre-forking web server
# See: https://httpd.apache.org/docs/2.4/mod/prefork.html
LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

# worker MPM: Multi-Processing Module implementing a hybrid
# multi-threaded multi-process web server
# See: https://httpd.apache.org/docs/2.4/mod/worker.html
#
#LoadModule mpm_worker_module modules/mod_mpm_worker.so

# event MPM: A variant of the worker MPM with the goal of consuming
# threads only for connections with active processing
# See: https://httpd.apache.org/docs/2.4/mod/event.html
#
#LoadModule mpm_event_module modules/mod_mpm_event.so

Comment out prefork MPM and activate worker MPM and the file should look like:

# Select the MPM module which should be used by uncommenting exactly
# one of the following LoadModule lines:

# prefork MPM: Implements a non-threaded, pre-forking web server
# See: https://httpd.apache.org/docs/2.4/mod/prefork.html
#LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

# worker MPM: Multi-Processing Module implementing a hybrid
# multi-threaded multi-process web server
# See: https://httpd.apache.org/docs/2.4/mod/worker.html
#
LoadModule mpm_worker_module modules/mod_mpm_worker.so

# event MPM: A variant of the worker MPM with the goal of consuming
# threads only for connections with active processing
# See: https://httpd.apache.org/docs/2.4/mod/event.html
#
#LoadModule mpm_event_module modules/mod_mpm_event.so

When that is done we just need to restart our webserver with:

systemctl restart httpd.service

and we’re all set.

...
Architecture:   64-bit
Server MPM:     worker
  threaded:     yes (fixed thread count)
    forked:     yes (variable process count)
Server compiled with....
...