Voiced by Amazon Polly |
Overview
Concurrency in programming allows multiple tasks to run simultaneously, improving performance and efficiency. In Python, multithreading and multiprocessing are two primary approaches to achieve concurrency. While they may seem similar, they serve distinct purposes and are suited for different tasks. This blog dives into the differences, use cases, and real-world examples of multithreading and multiprocessing in Python, helping you choose the right tool for your project.
Pioneers in Cloud Consulting & Migration Services
- Reduced infrastructural costs
- Accelerated application deployment
Multithreading
Multithreading involves running multiple threads within the same process. A thread is a lightweight unit of execution that shares the same memory space as other threads in the process. Python’s threading module enables multithreading, but the Global Interpreter Lock (GIL) in CPython limits true parallel execution for CPU-bound tasks. This makes multithreading ideal for I/O-bound tasks, where threads spend time waiting for external resources like network responses or file operations.
Key Characteristics of Multithreading
- Threads share memory, reducing overhead but requiring synchronization (e.g., locks) to avoid race conditions.
- Best for I/O-bound tasks like web scraping or downloading files.
- Limited by the GIL for CPU-bound tasks, preventing full CPU utilization.
Multiprocessing
Multiprocessing creates multiple independent processes, each with its own memory space and Python interpreter. The multiprocessing module in Python allows true parallelism by bypassing the GIL, making it suitable for CPU-bound tasks like data processing or mathematical computations. However, inter-process communication (IPC) and process creation introduce higher overhead than threads.
Key Characteristics of Multiprocessing
- Processes are isolated, eliminating the need for locks but requiring IPC mechanisms like pipes or queues.
- It is ideal for CPU-bound tasks like image processing or machine learning model training.
- Higher memory and startup overhead due to separate memory spaces.
Multithreading vs Multiprocessing: A Comparison
To understand when to use each approach, let’s compare them across key dimensions:
Example 1: Web Scraping (Multithreading)
Imagine you’re building a tool to scrape product prices from multiple e-commerce websites. This is an I/O-bound task because most of the time is spent waiting for HTTP responses. Multithreading shines here, as threads can handle multiple requests concurrently while sharing the same memory for storing results.
Here’s a simplified Python script using the threading module to scrape multiple URLs:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 |
import threading import requests from queue import Queue urls = ["https://example.com/page1", "https://example.com/page2"] results = Queue() def scrape_url(url): response = requests.get(url) results.put((url, response.status_code)) threads = [] for url in urls: t = threading.Thread(target=scrape_url, args=(url,)) threads.append(t) t.start() for t in threads: t.join() while not results.empty(): url, status = results.get() print(f"URL: {url}, Status: {status}") |
In this example, each thread fetches a web page, and the results are collected in a thread-safe queue. Multithreading reduces the total time by overlapping network delays.
Example 2: Image Processing (Multiprocessing)
Suppose you’re developing an application to resize thousands of images for a photo gallery. Image resizing is a CPU-bound task, as it involves intensive computations. Multiprocessing is ideal here, as each process can utilize a separate CPU core to process images in parallel.
Here’s a sample script using the multiprocessing module:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 |
from multiprocessing import Pool from PIL import Image import os def resize_image(image_path): img = Image.open(image_path) img = img.resize((100, 100)) img.save(f"resized_{os.path.basename(image_path)}") return f"Processed {image_path}" image_paths = ["image1.jpg", "image2.jpg", "image3.jpg"] if __name__ == "__main__": with Pool(processes=3) as pool: results = pool.map(resize_image, image_paths) for result in results: print(result) |
In this script, the Pool class distributes image paths across multiple processes, each resizing an image independently. This approach maximizes CPU utilization and speeds up the task.
Conclusion
Multiprocessing shines in CPU-bound tasks like image processing, leveraging multiple cores for true parallelism. Understanding their strengths, limitations, and real-world applications enables you to make informed decisions to optimize your Python programs.
Drop a query if you have any questions regarding Multithreading or multiprocessing and we will get back to you quickly.
Empowering organizations to become ‘data driven’ enterprises with our Cloud experts.
- Reduced infrastructure costs
- Timely data-driven decisions
About CloudThat
CloudThat is a leading provider of Cloud Training and Consulting services with a global presence in India, the USA, Asia, Europe, and Africa. Specializing in AWS, Microsoft Azure, GCP, VMware, Databricks, and more, the company serves mid-market and enterprise clients, offering comprehensive expertise in Cloud Migration, Data Platforms, DevOps, IoT, AI/ML, and more.
CloudThat is the first Indian Company to win the prestigious Microsoft Partner 2024 Award and is recognized as a top-tier partner with AWS and Microsoft, including the prestigious ‘Think Big’ partner award from AWS and the Microsoft Superstars FY 2023 award in Asia & India. Having trained 850k+ professionals in 600+ cloud certifications and completed 500+ consulting projects globally, CloudThat is an official AWS Advanced Consulting Partner, Microsoft Gold Partner, AWS Training Partner, AWS Migration Partner, AWS Data and Analytics Partner, AWS DevOps Competency Partner, AWS GenAI Competency Partner, Amazon QuickSight Service Delivery Partner, Amazon EKS Service Delivery Partner, AWS Microsoft Workload Partners, Amazon EC2 Service Delivery Partner, Amazon ECS Service Delivery Partner, AWS Glue Service Delivery Partner, Amazon Redshift Service Delivery Partner, AWS Control Tower Service Delivery Partner, AWS WAF Service Delivery Partner, Amazon CloudFront Service Delivery Partner, Amazon OpenSearch Service Delivery Partner, AWS DMS Service Delivery Partner, AWS Systems Manager Service Delivery Partner, Amazon RDS Service Delivery Partner, AWS CloudFormation Service Delivery Partner, AWS Config, Amazon EMR and many more.
FAQs
1. How can I share data between processes in multiprocessing?
ANS: – You can use multiprocessing.Queue, multiprocessing.Pipe, or shared memory, to communicate between processes.
2. Is multithreading faster than multiprocessing?
ANS: – It depends on the task. Multithreading is faster for I/O-bound tasks, while multiprocessing is better for CPU-intensive operations.
WRITTEN BY Aiswarya Sahoo
Comments