You can review and manage the active PHP configuration of your subdomains on the PHP Settings page of the Control Panel, along with some diagnostic information that is specific to the PHP-FPM handler.
When you click on the "Manage" button next to one of your subdomains, a page with the PHP settings that pertain to that particular subdomain will be shown.
If FPM with OPcache is chosen as the PHP handler, you can click on the "Status" button to display an additional list of status information. This information is relevant to the performance and load of your website.
Here is a list of the diagnostic values that you can review, along with the meaning of each one:
|Accepted conn||Number of requests that have been accepted and processed.|
|Active processes||Number of active PHP-FPM processes that accept requests.|
|Idle processes||Number of processes that are idle.|
|Listen queue||This value shows the number of requests that are waiting to be processed.|
|Listen queue len||This is the size of the queue of pending connections.|
|Max active processes||This is the greatest number of active processes that has been reached since the PHP-FPM master process was started.|
|Max children reached||Shows the number of times the PHP-FPM process limit has been hit when FPM tried to start more processes.|
|Max listen queue||Shows the largest number of requests in the queue since the master PHP-FPM process was started.|
|Pool||This is the name of the FPM pool. Usually, this will be set to the name of the subdomain.|
|Process manager||Type of process management strategy chosen for your website. On our servers, this is set to "ondemand".|
|Slow requests||Number of requests that have taken more time to be processed than a configured timeout.|
|Start since||Shows how many seconds the master PHP-FPM process has been running for.|
|Start time||Shows when the master PHP-FPM process was started.|
|Total processes||Number of all PHP-FPM processes that are currently running.|
The most important metrics you should pay attention to are the "Max children reached" and "Listen queue" ones.
Max children reached
This value will be incremented whenever the PHP-FPM master process reaches the maximum number of processes it can start in order to handle requests.
If this value is not zero, this means that there have been more requests to your website than can be comfortably handled by your hosting service, and requests have started piling up on a queue for processing. This may make your site slower than usual, and it may also be an indication of other problems.
This value shows the number of requests pending processing. If there are requests in the queue, this may mean that your website is overloaded or there is some other problem that causes it to be slower than usual.