There are these two ways of running PHP-FPM. I know that nothing is bullet-proof in tech, but what are the pros and cons from both methods?
The difference is mainly the added overhead of using the full network stack to "pack" and "unpack" every piece of data. Mind you that the overhead is negligible for most deployments
Using a socket (e.g. listen = '/tmp/php-fpm.sock') makes sense when both the front-end (e.g. Nginx) and php-fpm are in the same box and
Using a TCP connection (e.g. listen = 127.0.0.1:9000) makes sense if you want to de-couple the front and the back-end, for example, if you decide to scale up your environment by having a single Nginx receiving connections and passing the work via the network to a cluster of php-fpm boxes
Every environment is different, so as always, the only true option is to start with the one setup that seems right, load-test, and keep measuring the performance so you can try different options as your load requirements evolve (normally, you go with the one that is cheaper to implement or easier to maintain, since both are solid, battle-tested approaches)