Top 30 Python Interview Questions & In-Depth Code Solutions (2026 Edition)

Introduction: Cracking the Modern Python Technical Interview

Python remains one of the world's most popular programming languages for backend engineering, data science, automation, and cloud infrastructure. When interviewing for fresher and junior developer roles, hiring managers look beyond basic syntax; they evaluate your grasp of Python's memory management, data model, performance characteristics, and object-oriented architecture.

1. How Does Python Handle Memory Management & Garbage Collection?

Python uses Reference Counting and a Generational Cyclic Garbage Collector.

import sys
data = ["Django", "Python", "SQLite"]
print(f"Reference Count: {sys.getrefcount(data) - 1}")

2. What is the Global Interpreter Lock (GIL)?

The GIL is a mutex in CPython that prevents multiple native threads from executing Python bytecode simultaneously, avoiding race conditions in reference counting.

3. Mutable vs Immutable Default Argument Gotcha

def append_student_safe(name, student_list=None):
    if student_list is None:
        student_list = []
    student_list.append(name)
    return student_list