How do I implement the mark-and-sweep garbage collection algorithm?

Can you explain how to implement the mark-and-sweep garbage collection algorithm?

Sure! The mark-and-sweep algorithm consists of two phases: marking and sweeping. In the marking phase, you traverse the object graph and mark all reachable objects. In the sweeping phase, you go through the memory and collect all unmarked objects.

What data structures do I need for the marking phase?

You'll typically need a stack or a queue to keep track of the objects that need to be marked. A set can also be useful to track which objects have already been marked.

How do I handle cyclic references during marking?

Cyclic references can be handled by ensuring that you only mark each object once. Using a set to track marked objects helps prevent infinite loops.

Can you give me a simple code example?

Certainly! Here's a basic example in Python:

class Node:
    def __init__(self):
        self.children = []

    def add_child(self, child):
        self.children.append(child)

# Mark phase
marked = set()

def mark(node):
    if node not in marked:
        marked.add(node)
        for child in node.children:
            mark(child)

# Sweep phase
all_objects = [...]  # List of all objects
for obj in all_objects:
    if obj not in marked:
        collect(obj)  # Collect unmarked objects