Table of Contents

• What Is Concurrency?
• What Is Parallelism?
• When Is Concurrency Useful?
• When to Use Concurrency
• Conclusion

Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Speed Up Python With Concurrency

If you’ve heard lots of talk about asyncio being added to Python but are curious how it compares to other concurrency methods or are wondering what concurrency is and how it might speed up your program, you’ve come to the right place.

In this article, you’ll learn the following:

• What concurrency is
• What parallelism is
• How some of Python’s concurrency methods compare, including threading, asyncio, and multiprocessing
• When to use concurrency in your program and which module to use

This article assumes that you have a basic understanding of Python and that you’re using at least version 3.6 to run the examples. You can download the examples from the Real Python GitHub repo.

Free Bonus: 5 Thoughts On Python Mastery, a free course for Python developers that shows you the roadmap and the mindset you’ll need to take your Python skills to the next level.

Take the Quiz: Test your knowledge with our interactive “Python Concurrency” quiz. Upon completion you will receive a score so you can track your learning progress over time:

What Is Concurrency?

The dictionary definition of concurrency is simultaneous occurrence. In Python, the things that are occurring simultaneously are called by different names (thread, task, process) but at a high level, they all refer to a sequence of instructions that run in order.