PHP service maximum sub-processes
This option sets the limit on the number of simultaneous requests that will be served,
when PHP scripts for this domain setup to run via FPM, the number of child processes
will be created when pm option is set to static and the maximum number of
child processes could potentially be created when pm option is set to dynamic.
When PHP scripts for this domain setup to run via FCGI, PHP child process management
should always be disabled, which will only route one request at a time to application processes
it has spawned. By default, and with the environment variable setting PHP_FCGI_CHILDREN=0,
PHP child process management is disabled.