How to determine what is causing high RAM usage on Plesk server?

Question

At Tools & Settings > Server Information memory usage is near 100%.

How to determine what is causing high RAM usage?

Note: Plesk can only monitor the usage as it extracts the actual usage from the Operating System.

Answer

Plesk Repair Kit extension includes functionality to monitor in real-time CPU and RAM usage per subscription.

1. Log into Plesk;
2. Verify that Plesk Repair Kit extension is installed and listed in Extensions > My Extensions. Install the extension if it is not installed.
3. Go to Tools & Settings > Process List and turn on Auto-update of resource usage option. Click Memory Usage to filter the processes by RAM consumption: