How to limit php-cgi processes?


After posting, I found another post about website options:
This helped me to get the php-options to show up on a virtual server configuration (website options).
My question is:
How to limit the number of processes on Fastcgid execution mode?

I just set up my new server and after years of using Webmin, I started using Virtualmin with this one.
And I must say: Fabulous, I am impressed.
I used the installationscript on a fresh installation:

  • Centos 7.4 minimal on my 4 GByte RAM server
  • Configuration steps of Virtualmin all done.
  • Recheck of configuration all OK with 3 php versions:
    The following PHP versions are available : 5.4.16 (/bin/php-cgi), 7.0.10 (/opt/rh/rh-php70/root/usr/bin/php-cgi), 5.4 (mod_php)
    PHP-FPM support is available on this system.

I het setup 15 Virtual Servers (all Wordpress websites) and have all setup to PHP version 7.0

Now my question:
All websites are performing well and I decided to start a stress test with the ‘ab’-command.
The webserver was stressed and ‘ps aux | fgrep ‘php’’ showed a lot of ‘php-cgi’ processes (about 15) all consuming a lot of memory.
I want to limit the processes that are getting started.
I searched on Google and this forum, but I cannot find the answer.

Were can I setup the correct configuration for this limitation.
Should it be anywhere in the Virtual Hosts setting?
Or should I look for settings in the server itself (via Webmin or commandline)?

My configuration:
Operating system CentOS Linux 7.4.1708
Webmin version 1.870
Virtualmin version 6.02

I can choose the PHP version, but only between versions 7.0.1 and 5.4.16.
I cannot choose version 5.4 ???
And I can only choose the execution mode globally? At System settings -> Server templates (default) -> PHP options.
A cannot choose the execution mode for a single Virtual Server?

I would appreciate any help on this.

I find it refreshing and creative to find an institution like break away from the standard rules and find another way to see individuals as good candidates for their college. There’s so much more to a young person then how they fill in a box. The change works both ways, it forces the college to look at each student more carefully and allows the applicant to be more diverse.