Performance of Suspending Functions

When function a calls the function b, the virtual machine needs to store the state of a somewhere and the address where execution should return once b finishes. For storing this, we'll use a structure called a call stack. The call stack has limited space. When we've used it all, a StackOverflowError occurs. The problem is that when we suspend, we free a thread, and as a result, we clear our call stack. Therefore, the call stack is not useful when we resume.

Instead, the continuations serve as a call stack. Each continuation keeps the state where we suspended (as a label), the function’s local variables and parameters (as fields), and the reference to the continuation of the function called this function. One continuation references another, which references another, etc. As a result, our continuation is like a huge onion. It keeps everything that is generally on the call stack. Take a look at the ...