In dev, this is handled mostly by the OS with things like inotify, so it has little perf impact. In prod, you don't do it. Deployment implies sending a signal

In dev, this is handled mostly by the OS with things like inotify, so it has little perf impact. In prod, you don't do it. Deployment implies sending a signal like HUP to your app, so that it reloads the code gracefully. All in all, everybody is moving to thid, even php. This allows for persitent connexion, function memoization, delegation to threadpools, etc