Persistent connections not working

[MatthewAugier]

We have recently converted our CakePHP 2 project from PHP 5.6 to 7.4 (In docker containers, running on Centos), everything seemed to be going well until will added extra nodes into load (We have 4 nodes running through HaProxy to a Redis cluster). At this stage the number of redis connections (and pConnect) then went through the roof, and the system became unstable :(

We thought increasing the number of redis connection allowed on HaProxy may help (And it did for a while), played with timeouts on HaProxy, tweak other time out parameters, but nothing seemed to make a difference.

We tried various options we saw on here, and eventually set redis.pconnect.pooling_enabled=0 which then seems to of resolved this issue. Maybe it's a docker thing? Not sure, doesn't happen on php 5.6, we have around 120 php-fpm workers, and see around 120 netstat connections, with php 7.4 this was up past the 1,000+ mark, until we changed that setting and restarted the container - then we saw pretty much the same thing as the php 5.6 container with 120 connections again (both had same php.ini file)

Just writing this in case anyone else has an issue :)