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Asynchronous Programming in Python
Asynchronous Programming in Python

Asynchronous Programming in Python: Apply asyncio in Python to build scalable, high-performance apps across multiple scenarios

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Profile Icon Nicolas Bohorquez
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₱2296.99
Paperback Nov 2025 202 pages 1st Edition
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Arrow left icon
Profile Icon Nicolas Bohorquez
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₱2296.99
Paperback Nov 2025 202 pages 1st Edition
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Asynchronous Programming in Python

Summary

In this chapter we have informally introduced several key terms and concepts. In the next chapter we will go deep into actual Python constructs for multiprocessing and multithreading, including problems in which those techniques bring more value.We learned an intuitive way about how to distinguish synchronous and asynchronous solutions to well-defined problems. Then we translated those ideas into standard computer science terminology. This will allow us to go deeper into the particulars of each concept as we focus on specific coding solutions. In Chapter 2 we will embark on the practical approach by coding and comparing the multiprocessing and multithreading solutions for a vanilla implementation of a CPU-intensive problem.

Technical requirements

In this chapter we will show different solutions to a common problem. To run the code, which is available in the Chapter02 folder of the Github repo at https://github.com/PacktPublishing/Asynchronous-Programming-in-Python, we recommend creating a new virtual environment inside the folder and then running each Python file to check its output. No external packages are required but this way you can isolate your execution from the common Python environment of your computer:

$ python3 -m venv .env
$ source .env/bin/activate

Understanding concurrency and parallelism

Concurrency refers to the number of simultaneous tasks a system executes. Computers’ processors execute atomic operations at amazing speed, but they execute them one at a time. The result is that it looks like they are executing non-atomic tasks simultaneously.

To illustrate the idea, the following diagram shows two programs, each of which consists of three atomic operations: a processing task, reading a long file, and finally, another processing task:

Figure 2.1: Two concurrent programs being executed by a single processor

Imagine that both programs are launched at the same time. The processor executes the first atomic task of one of them and when there is a blocking operation that depends on a resource other than the processing unit, it uses the interruption mechanism to execute the first task of the second program. Both programs are executed concurrently by the processor.

Python offers several mechanisms to handle...

Applying multiprocessing and multithreading

Applying multiprocessing or multithreading techniques to any code isn’t a good choice; concurrency and parallelism are best reserved for the problem spaces where they provide the best results. As a rule of thumb, if a problem is input- or output-bound, it is better suited to being solved by increasing the concurrency handling of the system. If the problem requires more processing than data management, it is CPU-bound, and then multiprocessing is the best approach.

Usually, however, it is not that simple. Distributed systems, with their reliance on network communication, inherently have I/O characteristics that make them more suitable for the application of concurrency management techniques, while some of the components of the distributed systems could use the power of local/distributed processors to accelerate execution (e.g. when a specific large task is distributed across multiple parallel processors with a framework like MapReduce...

Detecting embarrassingly parallel workloads

Applying a simple function over a loop is a good example of a so-called embarrassingly parallel workload, which means that an easy optimization that can result in improved performance is to use multithreading or multiprocessing techniques to speed up the calculations. More broadly, the basic criterion you should check before trying to implement a parallelization optimization is that the sub-units of work making up your task are completely independent. In the previous example, the distance calculation for cities A and B is completely independent of the B to C case. You can find a simple example of an embarrassingly parallel workload in the repository file Chapter 2/embarrassingly.py, the code being a simple math operation:

import time
import multiprocessing
def square_number(n):
    time.sleep(0.001)
    return n * n
def serial_square_list(numbers):
    return [square_number(n) for n in numbers]
def parallel_square_list(numbers, num_processes...

Summary

In this chapter we have explored the basics of multiprocessing/multithreading applied to a classic embarrassingly parallel problem to discover that the apparently complicated calculations were less of an overhead than the context-switching cost of the parallelization techniques. Then, we discussed the importance of testing thread safety when you work with the threading module or similar. Finally, some of the most interesting well-known problems for which parallelization could offer benefits were mentioned. With these tools, you should be able to evaluate whether a workload is a good fit for the application of such kinds of optimization.

The next chapter will go deeper into practice with the implementation of simple solutions that take advantage of Python’s cooperative multitasking capabilities: generators and coroutines will be used to improve vanilla solutions for a CPU-intensive problem. Those tools, along with those discussed here, form the basis for understanding...

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Key benefits

  • Understand core principles and theory behind async programming in Python
  • Measure the impact of async techniques in practical, real-world use cases
  • Apply async patterns in software design and data-oriented architectures

Description

Asynchronous programming is one of the most effective but often misunderstood techniques for building fast, scalable, and responsive systems in Python. While it can significantly improve performance, efficiency, and sustainability, using async without a clear understanding of its trade-offs can lead to fragile designs and hard-to-debug issues. This book offers a structured approach to applying asynchronous programming in Python. It begins with a conceptual framework to help you distinguish between synchronous and asynchronous execution models, and shows how async relates to other concurrency strategies such as multithreading and multiprocessing. From there, you will explore the core tools available for building async applications in Python. You will also learn how to measure the impact of async programming in practical scenarios, profile and debug asynchronous code, and evaluate performance improvements using real-world metrics. The final chapters focus on applying async techniques to common cloud-based systems, such as web frameworks, database interactions, and data-pipelines tools. Designed for developers looking to apply async programming with confidence, this book blends real-world examples with core concepts to help you write efficient, maintainable Python code.

Who is this book for?

This book will help Python developers who want to understand and apply the asynchronous programming model in application development, data analysis, and orchestration scenarios. Junior developers, data engineers,, and tech leads will also benefit from the application design examples.

What you will learn

  • Use generators, coroutines and async/await to build scalable Python functions
  • Explore event loops to manage concurrency and orchestrate async flow
  • Compare concurrency models to choose the right async strategy
  • Optimize I/O-intensive programs to improve system throughput and efficiency
  • Build async services using real-world APIs and popular Python libraries
  • Apply structured concurrency and design patterns for cleaner async design
  • Test and debug async Python code to ensure reliability and stability
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Table of Contents

13 Chapters
Synchronous and Asynchronous Programming Paradigms Chevron down icon Chevron up icon
Identifying Concurrency and Parallelism Chevron down icon Chevron up icon
Generators and Coroutines Chevron down icon Chevron up icon
Implementing Coroutines with Asyncio and Trio Chevron down icon Chevron up icon
Assessing Common Mistakes in Asynchronous Programming Chevron down icon Chevron up icon
Testing and Asynchronous Design Patterns Chevron down icon Chevron up icon
Asynchronous Programming in Django, Flask and Quart Chevron down icon Chevron up icon
Asynchronous Data Access Chevron down icon Chevron up icon
Asynchronous Data Pipelines Chevron down icon Chevron up icon
Asynchronous Computing with Notebooks Chevron down icon Chevron up icon
Unlock Your Exclusive Benefits Chevron down icon Chevron up icon
Other Books You May Enjoy Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon
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