How does RTC handle dev updates loaded during a working day

I know what happens when loading various types of changes into a classic environment during the working day, but it struck me I have no idea what happens under RTC. If you change a codeunit or table on 2015 while users are in the system, what actually occurs? Does the server rebuild the .net assemblies as soon as any executing code finishes or does it attempt to do it immediately? If so how does that affect the users?
Note: I'm not saying I think this is a good practice or that I want to do this, but I think it prudent I understand the impact of such things given that my place of work will be upgrading very soon.