Top 25 Python Interview Question for Experienced

1. What is the Global Interpreter Lock (GIL) in Python?

The GIL is a mutex that allows only one thread to execute in the CPython interpreter at a time, even on multi-core systems. It prevents race conditions but limits concurrency in CPU-bound threads.

2. Explain the difference between deep copy and shallow copy.

A shallow copy copies the outer object but references the same inner objects. A deep copy recursively copies all objects, creating entirely independent objects. Use copy.copy() for shallow and copy.deepcopy() for deep copy.

3. What are metaclasses in Python?

Metaclasses are classes of classes that define how a class behaves. They control class creation and can be used to enforce coding standards, register classes, or modify class attributes.

4. What is a Python descriptor?

A descriptor is an object with methods like __get__, __set__, and __delete__, used to manage the attributes of other classes. Descriptors are the basis of Python’s property system.

5. Explain the use of decorators in Python.

Decorators are functions or classes that modify the behavior of another function or method using the @decorator syntax. They are commonly used for logging, access control, and memoization.

6. What is monkey patching in Python?

Monkey patching is the practice of modifying or extending code at runtime, often by dynamically altering classes or modules. It’s useful in testing but can make code harder to maintain.

7. How does memory management work in Python?

Python uses reference counting and a cyclic garbage collector to manage memory. When an object’s reference count drops to zero, it is eligible for garbage collection.

8. What is the difference between @staticmethod and @classmethod?

@staticmethod does not take self or cls as a parameter and behaves like a plain function inside a class. @classmethod receives the class as the first argument and can modify class state.

9. How is exception handling implemented in Python?

Python uses try, except, else, and finally blocks. You can catch specific exceptions, use multiple except clauses, and define custom exceptions by subclassing Exception.

10. What are generators and how do they differ from regular functions?

Generators use yield to produce a sequence of values lazily, one at a time, and maintain their state between calls. They are memory efficient compared to returning large lists.

11. Explain the purpose and usage of context managers.

Context managers manage resource setup and teardown using with. They implement __enter__ and __exit__, commonly used with files or database connections.

12. What are Python’s data model magic methods?

Magic methods like __init__, __str__, __len__, __getitem__, and __add__ allow operator overloading and customization of class behavior.

13. How do you implement a singleton pattern in Python?

Use a metaclass or decorator to ensure only one instance of a class is created. This is done by storing and returning the instance on subsequent calls.

14. What is the difference between is and ==?

is checks for object identity (same memory location), while == checks for value equality.

15. What is the difference between a module and a package?

A module is a single .py file, while a package is a directory with an __init__.py file that can contain multiple modules or sub-packages.

16. How does Python’s garbage collection work?

Python uses reference counting and a cyclic garbage collector that works in generations to detect and clean up unreachable objects in memory.

17. What are type hints and how are they used?

Type hints provide optional type annotations to variables and function signatures, helping with code readability and static analysis tools like mypy.

18. Explain the difference between synchronous and asynchronous programming in Python.

Synchronous code runs sequentially and blocks until completion. Asynchronous code uses async/await to run tasks concurrently, ideal for I/O-bound operations.

19. What is the difference between new and init?

__new__ creates a new instance (used mainly with immutable types), while __init__ initializes it after creation.

20. How do you handle circular imports in Python?

You can resolve circular imports by using local imports inside functions, restructuring code, or using import aliasing and delaying imports.

21. What are data classes and when should they be used?

Data classes (from Python 3.7) are used to reduce boilerplate when creating classes that mostly store data. They auto-generate __init__, __repr__, and __eq__.

22. What is duck typing in Python?

Duck typing is a dynamic typing style where an object’s behavior is determined by the methods and properties it implements rather than its actual type.

23. What is the purpose of slots?

__slots__ is used to declare a fixed set of attributes, saving memory by preventing the creation of a per-instance __dict__.

24. How does Python’s asyncio event loop work?

The asyncio event loop schedules and runs asynchronous tasks, handling I/O operations concurrently without using multiple threads or processes.

25. What is the difference between a coroutine, a task, and a future in asyncio?

Coroutine: A function defined with async def, which can be awaited.
Task: A coroutine wrapped and scheduled to run in the event loop.
Future: An object representing a result that hasn’t been computed yet.

Request more information

Top 25 Python Interview Question for Experienced