How to use QPluginLoader to load plugin as a service so the main app won't crash?

[wysota]

So this type of things are called a master-slave architecture? so in my case that would be a plugin master-slave architecture?

Your "plugin core" is a master that communicates with the other processes that do slave work on its behalf. It's a very complex architecture when talking about processes. I suggest you avoid it and use regular plugins that can crash your app. Implement them properly and they will not crash.