Exploring Coroutines in PHP

That's in no way lightweight though, and most languages can easily do the same. Just launch multiple instances/VMs/processes. That's having multiple separate OS processes, each having everything that is needed to run PHP, and having no way to communicate with each other, other than what you implement. No channels, no task distribution, no queue on which to sync and take tasks from, no signaling of all processes being done and then accumulating the results. That is why you then need something like RabbitMQ or other things, and it does not mitigate the heaviness of the approach.

It is kinda funny, that you mention RabbitMQ, which is written in Erlang, which is famous for its lightweight processes. But also compare the approach with thread pools built into the standard libraries in other languages. And even many of those are heavy weight compared to Erlang's lightweight processes.

PHP is not about lightweight, it's about rapid development. A lot of implementations in PHP are dead simple and can be debugged even by beginners.

You generally do not implement efficient systems in php, they are easy to debug, fast to code and quick to fix though.

PHP's approach is simple though, and in my experience that simplicity pays off when you do start scaling the systems.

In other systems once you get beyond a single machine you need that external communication mechanism anyway, and now you have multiple classes of comms which introduces bugs and complexity and performance cliffs.

In PHP you just throw another server at it, it'll act the same as if you just added another process. Nice linear scaling and simple to understand architectures.

Man I miss working in PHP

Most of the time you don’t really need to think about memory management either as the memory for the process is simply reset on every request.