I'm running CentOS 64 bit, and just found out I am running prefork MPM on my dual quad Xeon. I was told worker will give me lower memory usage and higher performance, since I run a very high traffic website.

If this is true, how do I do it?

4 Answers 4


Edit: /etc/sysconfig/httpd



Restart, voila!

  • Hi @RafiqManiar, by restart do you mean Apache or the whole server here?
    – ericn
    Feb 25, 2013 at 5:04
  • 4
    Restart apache. sudo service httpd restart Feb 25, 2013 at 8:31
  • 2
    CentOS 7. i am getting this: /usr/sbin/apachectl: line 137: /usr/sbin/httpd.worker: No such file or directory
    – YumYumYum
    Jun 12, 2015 at 8:26

CentOS 6x:

modify file: /etc/sysconfig/httpd


CentOS 7x:

$ cat /etc/httpd/conf.modules.d/00-mpm.conf

    #LoadModule mpm_prefork_module modules/mod_mpm_prefork.so
    LoadModule mpm_worker_module modules/mod_mpm_worker.so
    #LoadModule mpm_event_module modules/mod_mpm_event.so


  • 1
    From the file /etc/sysconfig/httpd for apache 2.4 # Note: With previous versions of httpd, the MPM could be changed by # editing an "HTTPD" variable here. With the current version, that # variable is now ignored. The MPM is a loadable module, and the # choice of MPM can be changed by editing the configuration file # /etc/httpd/conf.modules.d/00-mpm.conf. Oct 21, 2017 at 23:54

Edited: /etc/sysconfig/httpd

And uncommented:


After restarting httpd (service httpd restart) I get the following error:

Stopping httpd:                                            [  OK  ]
Starting httpd: httpd.worker: Syntax error on line 222 of /etc/httpd/conf/httpd.conf: Syntax error on line 9 of /etc/httpd/conf.d/php.conf: Cannot load /etc/httpd/modules/libphp5-zts.so into server: /etc/httpd/modules/libphp5-zts.so: cannot open shared object file: No such file or directory

You might need to install php-zts though.

yum install php-zts

After that no more error messages and httpd is starting normally with module worker active.


-- Redhat Enterprise Linux 6

php-zts in RHEL is found in the "optional" repository:

# subscription-manager repos --enable rhel-6-server-optional-rpms
Repository 'rhel-6-server-optional-rpms' is enabled for this system.
# yum install php-zts

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