Steps to reproduce:

I have around 4000 NVPS and 32 GB of memory on the Zabbix server. Database is hosted on a different server and it runs with 3 proxies. Had some issues for a while now but it was not consistent, it was crashing every couple of weeks with out of memory. 

It is now happening way more often, at least every week and now it happened last friday and it happened again this morning.

I can see by the graphs that memory usage is constantly growing after reboot from 40% to 90% and then I do a preventive restart of the zabbix server on a trigger so we not impacted that much.

I am running on RHEL 7 and I will be happy to provide you with everything you need for investigation very fast.

I am attaching a couple of screenshots to see memory usage of the server.

Thank you for your time !