Memory on VPS. How to understand who eats and how to limit consumption?

Question

Swap

Hello.
There is a VPS server on CentOS 6.7, VestaCP, 3 sites on Wordpress (one of them is a multisite, but everything is cached there).
And so the problem - sooner or later the server dials the swap to the maximum and goes offline (the hoster cuts it off).
What to do?

Answer 1

1. Refuse Apache, you don't need it, use nginx+php-fpm
2. Refuse malicious software called VestaCP
3. See spamd from SpamAssassin there? Why is he there at all? Here you also pass it.
4. Disable swap altogether.
5. Set up OOM-killer

Answer 2

cut apache workers
cut mysql memory consumption
turn off swap if there is enough memory

Answer 3

Recently, I encountered this myself on West.
this article helped https://habrahabr.ru/post/242011/ , so far only regarding Prefork.