PHP-FPM processes of a domain run for too long

Symptoms

• PHP-FPM processes of a domain run for too long, consuming too much memory and causing server malfunction.
• Site contains a never ending script. 
• No DDoS attacks detected - can be checked using the How to find what sites are or were under DDoS attack article.
• pm.max_requests parameter is set to unlimited.

Cause

PHP application code doesn't finish, and due to max_requests is unlimited, the php-fpm processes are not being rotated and increasing in resources consumption over time.

Resolution

1. Log in to Plesk.
2. Set the pm.max_requests parameter to 100 in the menu Domains > example.com > PHP Settings and click OK or Apply in the bottom of the page to save the changes: