This code will create a coroutine using GlobalScope.launch will be suspended and when makeLogin() is finished she will be resumed and the same thing will happen when loadMovies() is called. You will understand more of this explication at the end of the article. That way, you can have the effect that you using multi threads when you actually using one, and because of that you often hear that coroutines are light threads. And to have that effect, the control is transferred from one function to another in a way that the exit point from the first function and the entry point to the second function is remembered, without changing the context. To not have this situation where A needs to wait for B, you need to make B run in a different thread and now A doesn't need to wait.Ĭoroutines are functions that are cooperative, functions where the control of how runs are made by the “user” and not the OS, so you can have the same effect of using different threads without really needing more the one. And this control of function B over A is made by the OS, B has to finish, so the OS can give control back to A.

When you call a function B from function A, A has to wait until B is finished to continue executing, this is what we call functions non-cooperative. You probably are a little confused right now and that's okay, Coroutine is a difficult concept to understand, so I will try to explain the best I can. Basically, they all think they were the master program, when in fact there is no master's program.

And if the processing modules communicate following these restrictions, each module may be made into a coroutine.Īnd what means to be made a Coroutine? It means that each module communicates with adjacent modules as if they were input or output subroutines. What does he mean about separability? A program organization is separable if is divided into processing modules that communicate with each other according to some restrictions. Years later, in 1963, he published an article called “ Design of a Separable Transition-diagram Compiler” and talks about the creation of a Cobol Compiler that has the design property of separability. The concept of coroutines was conceived in 1958 by Melvin Edward Conway and he was the first to apply the concept in an Assembly Program.

Kotlin internal function