Crafting Interpreters

garbage collection

A value is reachable if there is some way for a user program to reference it. A root is any object that the VM can reach directly without going through a reference in some other object. Most roots are global variables or on the stack.

reachability:

• All roots are reachable.
• Any object referred to from a reachable object is itself reachable.

Mark-Sweep Garbage Collection works in two phases:

• Marking – We start with the roots and traverse or trace through all of the objects those roots refer to.
• Sweeping – go through all the unmarked objects and free each one.