I want to run more than 800 PHP scripts in the background simultaneously on Linux. Each PHP script will execute forever, meaning it will not stop once it has started. Each script will send request and get response from the server. How much RAM do I need for that? Will it possible to run more than 800 scripts? What kind of hardware do I need?
You're probably doing it wrong. Since your scripts are I/O bound instead of CPU bound, an event loop will help you. That way you just need as many workers as CPU cores.
This approach does not only lower your required resources in terms of memory and CPU cycles, but also reduce the number of scripts you have to monitor.
There are various PHP implementations, here are the three most popular ones: