The issue with that to me is the concern of memory leaks. With PHP/FastCGI, it's not a problem because after every request, the memory is thrown away. You just

The issue with that to me is the concern of memory leaks. With PHP/FastCGI, it's not a problem because after every request, the memory is thrown away. You just need to trust that PHP-FPM itself doesn't leak. But that said, I do use https://reactphp.org/ https://reactphp.org/ occasionally for certain types of tasks (like running a websocket server) and that works great too, but it takes extra care to make sure not to use blocking IO and to take more care of memory management.