High CPU and memory usage by website

Symtopns

High CPU and memory usage by Apache process is reported by top command:

# top
2043 example 20 0 0 0 0 S 100.0 70.5 0:05.43 httpd

or

High CPU usage by php-fpm process is reported by top command: 

# top
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
...
2089 example 20 0 0 0 0 S 96.8 60.5 0:02.43 php-fpm

Cause

Apache module is used to serve PHP. It is the slowest engine available.

Resolution

If mod_php is used:

1. Log into Plesk UI.

2. Switch websites' PHP engine to FastCGI application served by Apache or to FPM application served by Apache (better option) via the tab Domains > example.com > Hosting Settings:

If "FPM Application server by Apache" is used:

Warning: Nginx does not support .htaccess rules. Code of some websites may not support FastCGI or PHP-FPM, so it is recommended to consult with website developer before switching the handler.

1. Log into Plesk UI.

2. Enable nginx web server if it is not enabled yet.

3. Enable to Nginx for affected domain. Open Subscriptions > example.com > Apache & nginx Settings > check option Proxy mode and press OK:

Note: on servers with high load, switch to Event mode at Tools & Settings > Apache Web server > MPM Mode

Additional information

• High CPU usage by Apache is shown in Health Monitor