Non-persistent MySQL connections are not being closed in Cacti.

Description

I have been investigating a problem with Cacti where it opens a new database connection on every 5 minute poll interval, and never closes them, eventually running the DB server out of connections, even with the max_connections set to 1000. It is a new install of Cacti, I am not upgrading.

Eventually I figured out that configuring Cacti to use persistent database connections solved the issue. So there is a workaround.

I am seeing the biggest problem with the long-running daemons, one for cacti itself called cactid, the other for a cacti plugin called flowview. The service for that one is called "flow-capture".

The cacti project is claiming that they have never had to worry about closing connections before and they think something probably changed in PDO.

This is the issue I opened on Cacti for the problem:

https://github.com/Cacti/cacti/issues/5401

PHP Version

PHP 8.1.2-1ubuntu2.13

Operating System

Ubuntu 22.04

Beginnen Sie damit, das Wachstum der Verbindungen in den cactid- und flow-capture-Daemons unter PHP 8.1.2 mit nicht persistenten MySQL-Verbindungen zu reproduzieren, wobei das verknüpfte Cacti-Issue als Kontext dient. Verfolgen Sie den Lebenszyklus der PDO-Verbindungen während wiederholter Abfragen im Abstand von fünf Minuten; als abgeschlossen gilt dies, wenn die Verbindungen freigegeben werden, anstatt sich anzusammeln, bis MySQL sein Limit erreicht.