10 Senior Python Developer Interview Questions | EPAM Anywhere (2023)

2. What is CPython?

Python is an interpreted language. Its code is first interpreted by another program (interpreter) and then compiled into something called bytecode. Bytecode is made out of bytes that represent the machine’s instructions. CPython is the implementation of Python whose bytecode is in the C programming language.

On the other hand, we have Jython which bytecode is in Java or other Python implementations.

We also have something called Cython, which is the compiled language used to create CPython extensions. The Cython language is a superset of Python that supports several C programming language features.

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3. What is LEGB in Python?

This is an example of sr Python developer interview questions related to scoping. When the Python interpreter is trying to look up a name, it uses the LEGB rule to resolve the names (variable, function, and other object names). It first checks for the existence of names in L, E, G, and B scopes in the order below:

  1. Local Scope: The area within a function body or a lambda expression.
  2. Enclosing Scope: Assume we have a function called outer which has a nested function. Enclosing scope (or nonlocal scope) is the area within the body of outer function.
  3. Global Scope: The names in this scope are visible to all code in one Python script (in one file having a .py extension).
  4. Built-in Scope: The names that exist in this scope are loaded when we run a Python shell/script. Keywords such as in, and, or, def, class and expressions like __main__, __file__ are some examples.
10 Senior Python Developer Interview Questions | EPAM Anywhere (4)10 Senior Python Developer Interview Questions | EPAM Anywhere (5)

4. What are the usages of nonlocal and global keywords in Python?

This interview question has a direct relationship with the previous one. The code sample below illustrates the usage of these two keywords:

5. What is GIL and why is it important?

GIL is one of the most controversial and important features of the CPython-based implementation of Python. GIL, or Global Interpreter Lock, is a construct/tool that makes sure that only one thread at a time can execute a Python program. In other words, this lock belongs to the Python interpreter and it uses it to lock a thread.

For example, thread T1 acquires GIL and does its job. While the Python interpreter is using GIL to lock T1, all other threads have to wait. After T1 finishes, it releases GIL and passes it to another thread T2 that needs it. The reason for the GIL presence is to make CPython thread-safe and not allow some threads to interfere with one another.

(Video) Python Mock Interview | Interview Questions for Senior Python Developers

6. How does Python handle memory management?

Before answering senior Python interview questions like this one, you must be aware that we are talking about the CPython implementation. Other Python implementations may have different rules and requirements for memory management.

Assume you have a Python script and you want to execute it. When you execute this file, the Python interpreter occupies some “area” of the RAM. This “area” itself is divided into two categories: the stack and the private heap.

Now assume that in this script we have declared a string object a = “hello”. When we execute this script, the CPython memory management system creates an object of type string on the private heap. This object contains three fields:

  • Type: This is a string (note that Python is a dynamically typed programming language, so it will understand your object type to store).
  • Value: This is “hello”.
  • Reference count: It shows the number of times that a has been referenced. For now, it is 1.

Now on the stack, the reference to a (that is stored on the private heap) is stored. There exists a tool called a garbage collector. The garbage collector’s job is to delete the objects (on the private heap) that are no longer referenced, meaning, it deletes the objects whose reference count reached zero. This way the garbage collector frees up some memory space for the Python interpreter.

7. Where should we use Python's multithreading, multiprocessing, and asyncio libraries?

To answer this question, we need some background knowledge. We divide the operations that we want our Python code to do into two categories:

  • CPU-bound operations such as parsing, image processing, string manipulation, and algorithms involving heavy calculations. We can use parallelism for these types of operations. Basically, parallel programming is when we create different processes to divide a job among them and they all do the job simultaneously. Each process has its own GIL, Python interpreter, memory space, and state information. In Python, we use the multiprocessing library to achieve parallelism.
  • IO-bound operations such as sending HTTP requests, querying data from databases, sending emails, and opening a file. We use concurrency for these operations. In Python, we can handle these operations using multithreading and asyncio libraries. Note that parallelism requires more resources than concurrency.

8. How does importing in Python work?

To answer this senior Python developer interview question, assume we have a directory called dir, inside which we have a Python script. When you import a module in this Python script, the Python interpreter tries to find your imported module in this order:

  1. It searches among other Python scripts inside the dir directory.
  2. Then it goes over the list of the directories that are set using the PYTHONPATH environment variable.
  3. Last, it searches through the default directories where Python files were installed. For example, 'C:\\Users\\user\\AppData\\Local\\Programs\\Python\\Python311\\Lib'
(Video) How to Prepare for a Python Senior Developer Interview

9. What is a closure in Python?

A closure is an inner/nested function that keeps the data regarding its enclosing scope even after the closure is called. To illustrate your answer to this interview question, you can provide this scenario for using closures for lazy evaluation:

10. How do you write scalable code in Python?

This is one of the most impactful and advanced senior Python interview questions. Scalability means creating services and microservices that can handle millions of users (large loads) without going down. This is a challenge that must be handled properly and writing scalable code is one way to make our service scalable.

Please be aware that we have to take into account many other components of creating a scalable project, such as systems design, DBMS, and infrastructure.

Below you can find some concepts of writing scalable code for Python Core to include in your answer to this interview question.

Use efficient data structures. For example, the time complexity of in operator is different depending on what iterable it has been used on.

  • On list/tuple 🡪 O(n) time complexity.
  • On dictionary/set 🡪 O(1) is the average case and O(n) is the worst case.

In the examples above, n is the length of the iterable.

Use parallelism. Dividing and running a CPU-bound operation using different processes can be a solution to boost the speed.

Design a distributed system. In a distributed system there are different machines that communicate with each other to do a job. Using libraries like Apache Spark or Ray can be a good approach for scalability.

Use caching. Assume there is an image that requires heavy processing and this image must be sent to many users. To address such requirements, we can process this image only once and cache/store the processed version in a variable. This way whenever we want this processed image, we can just make use of that variable and avoid processing the image again.


(Video) Top 100 Python Interview Questions | Python Programming | Crack Python Interview |Great Learning

Those were the top ten senior Python developer interview questions and answers for those looking to advance their career in tech. You can get more information about frequently asked technical interview questions in our comprehensive guide for dozens of roles and specializations to help you secure a job offer. Check it out:

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(Video) Django Mock Interview | Interview Questions for Senior Django Developers


How do I prepare for a Python developer interview? ›

Python Developer Interview Tips
  1. Ensure you know the ins and outs of Python frameworks, data structures, functions, and libraries.
  2. For technical questions, clearly explain the thought process used to arrive at the correct solution.
  3. Prep for questions related to soft skills such as communication, leadership, and teamwork.

What are the interview questions for Python developer? ›

Basic Python Interview Questions for Freshers
  • What is Python? ...
  • Python is an interpreted language. ...
  • What is the difference between lists and tuples? ...
  • What is pep 8? ...
  • What are the Key features of Python? ...
  • How is Memory managed in Python? ...
  • What is PYTHONPATH? ...
  • What are Python Modules?
Jan 10, 2023

How do you interview a senior developer? ›

Senior developer interview questions
  1. What are your preferred languages and why? ...
  2. How do you measure a team's performance? ...
  3. What does your quality control process look like for developing software? ...
  4. Tell me about a time when your team failed to deliver on expectations. ...
  5. What does your process for scaling systems look like?

What are the 5 hardest interview questions and answers? ›

The most difficult interview questions (and answers)
  • What is your greatest weakness?
  • Why should we hire you?
  • What's something that you didn't like about your last job?
  • Why do you want this job?
  • How do you deal with conflict with a co-worker?
  • Here's an answer for you.

What are the six P's of an interview? ›

Landing an interview doesn't mean landing the job, because selling your skills and abilities depends on you: Prepare, Practice, Presentation, Powerful Interview, Post-Interview, and Ponder the Position are the six Ps that ensure the best possible outcome for you and the interviewer.

What are 10 good interview questions and answers? ›

50+ most common job interview questions
  • Tell me about yourself.
  • Walk me through your resume.
  • How did you hear about this position?
  • Why do you want to work at this company?
  • Why do you want this job?
  • Why should we hire you?
  • What can you bring to the company?
  • What are your greatest strengths?
Jan 4, 2023

What are the top 10 interview questions and answers? ›

Top 10 Interview Questions and Best Answers
  • Tell Me About Yourself. ...
  • Why Are You the Best Person for the Job? ...
  • Why Do You Want This Job? ...
  • How Has Your Experience Prepared You for This Role? ...
  • Why Are You Leaving (or Have Left) Your Job? ...
  • What Is Your Greatest Strength? ...
  • What Is Your Greatest Weakness?
Dec 10, 2022

What are the 4 main uses of Python *? ›

Python is commonly used for developing websites and software, task automation, data analysis, and data visualization. Since it's relatively easy to learn, Python has been adopted by many non-programmers such as accountants and scientists, for a variety of everyday tasks, like organizing finances.

How do I pass a Python interview? ›

How to Stand Out in a Python Coding Interview
  1. Select the Right Built-In Function for the Job. Iterate With enumerate() Instead of range() ...
  2. Leverage Data Structures Effectively. Store Unique Values With Sets. ...
  3. Take Advantage of Python's Standard Library. ...
  4. Conclusion: Coding Interview Superpowers.

What are the top 3 interview mistakes? ›

Top 5 job interview mistakes
  • Being unprepared.
  • Dressing inappropriately.
  • Talking too much or not enough.
  • Criticising previous employers or colleagues.
  • Failing to ask questions.

What are the 3 C's of interview? ›

These three C's that we will examine are: Credibility; Competence; and Confidence. They are inextricably connected. I'm an introvert by personality type, but can interview with the best of them because of the successful implementation of these three C's.

What is the 80/20 rule in interviewing? ›

As a rule of thumb, it is recommended that you spend just 20% of your preparation time researching the company in question, and 80% of your time focusing on yourself and your relevant skills and experience.

What are 12 interview techniques? ›

12 Interview Tips to Impress Any Hiring Manager
  • Research the company and your interviewers. ...
  • Dress for the company. ...
  • Show up early to your interview. ...
  • Clarify your personal mission statement. ...
  • Be fully present. ...
  • Bring a copy of your resumé or portfolio. ...
  • Don't lie or overshare. ...
  • Be yourself.
Nov 9, 2021

How do you ace an interview 10 crucial tips? ›

Interview Tips: 10 Ways to Improve Interview Performance
  1. Practice Good Nonverbal Communication. ...
  2. Dress for the Job or Company. ...
  3. Listen. ...
  4. Don't Talk Too Much. ...
  5. Don't Be Too Familiar. ...
  6. Use Appropriate Language. ...
  7. Don't Be Cocky. ...
  8. Take Care to Answer the Questions.

What are the 10 top tips for great interviews? ›

  • Tell the truth. ...
  • Listen carefully to the interviewer. ...
  • Never slight a teacher, friend, employer, or your university. ...
  • Watch your grammar. ...
  • Be prepared for personal questions. ...
  • Wait for the interviewer to mention salary and benefits. ...
  • Don't expect a job offer at the first interview. ...
  • Close on a positive, enthusiastic note.

What are 5 key points to a great interview? ›

10 Things to do RIGHT in an interview
  • 1) Dressing the Part. ...
  • 2) Review the Questions The Interviewers Will Ask You. ...
  • 3) Do Enough Research on the Company. ...
  • 4) Be Respectful of the Interviewers. ...
  • 5) Good Non-Verbal Behavior.
  • 6) Be On Time to the Interview. ...
  • 7) Know all the Credentials of the Company and the Job you're Applying For.
Jan 7, 2022

What is the STAR method in interviews? ›

The STAR method is a structured manner of responding to a behavioral-based interview question by discussing the specific situation, task, action, and result of the situation you are describing.

What are the three 3 most important keys to success in interviews? ›

Employers rate showing enthusiasm (for the job, company, industry) and making eye contact as the most important keys to success at interviews. Since interviews are a conversation between the potential employee and the employer, speaking clearly (and loud enough) is also vital.

What is your biggest flaw interview? ›

How to answer What are you greatest weaknesses? Choose a weakness that will not prevent you from succeeding in the role. Be honest and choose a real weakness. Provide an example of how you've worked to improve upon your weakness or learn a new skill to combat the issue.

What are 4 tips for interviewing? ›

Interview tips
  • Review common interview questions. ...
  • Make a list of questions that you would like to ask during the interview. ...
  • Be prepared. ...
  • On the day of the interview, remember to:
  • Display confidence during the interview, but let the interviewer start the dialogue. ...
  • End the interview with a good impression.

What are 20 tips for great job interviews? ›

20 Strategies for Successful Job Interviews
  • Research the industry and organization. ...
  • Clarify your "selling points" and the reasons you want the job. ...
  • Anticipate the interviewer's concerns and reservations. ...
  • Prepare for common interview questions. ...
  • Line up your questions for the interviewer. ...
  • Practice, practice, practice!!!

What are the 5 Python principles? ›

SOLID Coding in Python
  • The Single-Responsibility Principle (SRP)
  • The Open-Closed Principle (OCP)
  • The Liskov Substitution Principle (LSP)
  • The Interface Segregation Principle (ISP)
  • The Dependency inversion Principle (DIP)
Jun 29, 2021

What are the 3 basic values can use in Python? ›

First up is a discussion of the basic data types that are built into Python. Here's what you'll learn in this tutorial: You'll learn about several basic numeric, string, and Boolean types that are built into Python.

What are the 3 types of programming in Python? ›

There are four main Python coding styles: imperative, functional, object-oriented, and procedural.

What are 3 benefits of Python? ›

Top Reasons to Learn Python
  • Data science.
  • Scientific and mathematical computing.
  • Web development.
  • Finance and trading.
  • System automation and administration.
  • Computer graphics.
  • Basic game development.
  • Security and penetration testing.
3 days ago

What are 7 tips for preparing for an interview? ›

Brush up on interview skills and common interview questions.
  1. Identify your selling points for this job. ...
  2. Be ready to tell the interviewer about yourself. ...
  3. Know why you're interested in this position at this company. ...
  4. Do some salary research. ...
  5. Prepare your stories. ...
  6. Familiarize yourself with the STAR method.

How do you crack the hardest interview? ›

Market yourself with sincerity and confidence, so that the interviewer knows your strengths and areas of expertise as clearly as possible. HRs expect candidates to give honest answers under every circumstance, as that proves their integrity and truthfulness. Listen and think for some time before giving an answer.

Why should we hire you as Python developer? ›

“Honestly, I possess all the skills and experience that you're looking for. I'm pretty confident that I am the best candidate for this job role. It's not just my background in the past projects, but also my people skills, which will be applicable in this position.

What are skills required for Python developer? ›

Knowledge of Python web frameworks and event-driven programming in Python. Basic understanding of front-end technologies. High attention to detail. Excellent communication and problem-solving skills.

How do you explain a project in Python developer interview? ›

In a Python interview, select the project that took pride in developing and explain the project with confidence. Start explaining the project with the problem statement. Explain the entire process of how you developed the solution. Also, explain the obstacles you faced in the process and how you solved them.

How do you handle stress and pressure? ›

2. Commit to a Positive Attitude
  1. Decide what you can do. Pinpoint which parts of the situation you have the power to change or influence for the better. ...
  2. Get support. Find someone to talk to about your situation. ...
  3. Care for yourself. Take especially good care of yourself when stress in your life is high.

What is your biggest strength? ›

Here are some examples of strengths you could mention.
  • Enthusiasm.
  • Creative thinking.
  • Task prioritization.
  • Discipline.
  • Determination.
  • Analytical thinking.
  • Communication skills.
  • Dedication.
Jan 4, 2023

What's your biggest achievement? ›

'My greatest achievement' examples could include: Giving a great presentation at work. Beating sales targets. Training for and completing a marathon.
  • Think About Your Values and Best Qualities, and Try to Highlight Them. ...
  • Research the Job and Company. ...
  • Be Honest. ...
  • Be Specific.

What a senior Python developer should know? ›

Senior Python Developer responsibilities include:

Building efficient server-side applications. Integrating front-end components into applications. Checking code from other developers and coaching junior team members.

What are the 5 key features of the Python programming language? ›

The following are some of the features in Python that are discussed below:
  • Easy to Code. Python is a very high-level programming language, yet it is effortless to learn. ...
  • Easy to Read. ...
  • Free and Open-Source. ...
  • Robust Standard Library. ...
  • Interpreted. ...
  • Portable. ...
  • Object-Oriented and Procedure-Oriented. ...
  • Extensible.
Oct 28, 2022

What is the salary of Python developer after 5 years? ›

A mid-career Python Developer with 4-9 years of experience earns an average salary of ₹8.3 Lakhs per year, while an experienced Python Developer with 10-20 years of experience earns an average salary of ₹18.3 Lakhs per year.

What is the salary of Python Dev? ›

Average ₱42,991 per month.

What is the most demand skills in Python? ›

Let have a look at the top 10 skills required to become a Python Developer:
  • Expertise In Core Python.
  • Good grasp of Web Frameworks.
  • Object Relational Mappers.
  • Road to Data Science.
  • Machine Learning and AI.
  • Deep Learning.
  • Understanding of Multi-Process Architecture.
  • Analytical skills.
Dec 13, 2022

Is Python developer stressful? ›

Python developers encounter stress like most other developers. Stress for programmers is not exclusive to Python developers. Whether you're a Python developer or not, it's important to find ways to handle stress as a software developer.

What is pep 8 in Python? ›

PEP 8, sometimes spelled PEP8 or PEP-8, is a document that provides guidelines and best practices on how to write Python code. It was written in 2001 by Guido van Rossum, Barry Warsaw, and Nick Coghlan. The primary focus of PEP 8 is to improve the readability and consistency of Python code.

What is polymorphism in Python? ›

The literal meaning of polymorphism is the condition of occurrence in different forms. Polymorphism is a very important concept in programming. It refers to the use of a single type entity (method, operator or object) to represent different types in different scenarios.

How many data types are there in Python? ›

In a programming language like Python, there are mainly 4 data types: String – It is a collection of Unicode characters (letters, numbers and symbols) that we see on a keyboard. Numerical – These data types store numerical values like integers, floating-point numbers and complex numbers.


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