Garbage collection basics in Compiler Design - Mini Project: Build & Apply

Garbage Collection Basics Database

📖 Scenario: You are building a simple database to track objects in memory for a garbage collector in a compiler design project. This database will help you understand how objects are allocated, referenced, and identified as garbage.

🎯 Goal: Create a database that stores objects with their IDs and reference counts, then identify which objects are eligible for garbage collection (those with zero references).

📋 What You'll Learn

Create a dictionary called objects with object IDs as keys and their reference counts as values.

Create a variable called threshold set to 0 to identify garbage objects.

Use a dictionary comprehension to create a new dictionary called garbage_objects containing only objects with reference counts equal to the threshold.

Add a final step to count the number of garbage objects and store it in a variable called garbage_count.

💡 Why This Matters

🌍 Real World

This project models how a garbage collector tracks and identifies unused objects in memory to free up space automatically.

💼 Career

Understanding garbage collection is important for compiler design, programming language development, and optimizing software performance.

1

Create the objects dictionary

Create a dictionary called objects with these exact entries: "obj1": 3, "obj2": 0, "obj3": 5, "obj4": 0, and "obj5": 2.

Compiler Design

# Create the objects dictionary with given IDs and reference counts
# Your code here

Need a hint?

Use curly braces {} to create a dictionary with keys and values separated by colons.

2

Set the garbage threshold

Create a variable called threshold and set it to 0 to represent the reference count that identifies garbage objects.

Compiler Design

objects = {"obj1": 3, "obj2": 0, "obj3": 5, "obj4": 0, "obj5": 2}
# Create the threshold variable set to 0
# Your code here

Need a hint?

Just assign the number zero to the variable threshold.

3

Identify garbage objects

Use a dictionary comprehension to create a new dictionary called garbage_objects that contains only the entries from objects where the reference count equals the threshold.

Compiler Design

objects = {"obj1": 3, "obj2": 0, "obj3": 5, "obj4": 0, "obj5": 2}
threshold = 0
# Create garbage_objects dictionary with objects having reference count equal to threshold
# Your code here

Need a hint?

Use {key: value for key, value in dictionary.items() if condition} syntax for dictionary comprehension.

4

Count garbage objects

Create a variable called garbage_count and set it to the number of entries in the garbage_objects dictionary.

Compiler Design

objects = {"obj1": 3, "obj2": 0, "obj3": 5, "obj4": 0, "obj5": 2}
threshold = 0
garbage_objects = {obj_id: ref_count for obj_id, ref_count in objects.items() if ref_count == threshold}
# Count the number of garbage objects and assign to garbage_count
# Your code here

Need a hint?

Use the len() function to count dictionary entries.