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handling concurrency in python

Wednesday, 15 March 2023

Python provides several libraries and features to handle concurrency, allowing you to execute multiple tasks concurrently and improve the performance of your applications. To demonstrate this concept, let's consider a complex example involving web scraping. Imagine you have a list of URLs, and you want to fetch the HTML content of each URL concurrently to speed up the process. We'll use the requests library for making HTTP requests and the asyncio library for handling asynchronous operations.


import asyncio

import requests

async def fetch_url(url):

    response = requests.get(url)

    return response.text

async def scrape_urls(urls):

    tasks = []

    for url in urls:

        task = asyncio.create_task(fetch_url(url))



    results = await asyncio.gather(*tasks)

    return results

async def main():

    urls = [






    results = await scrape_urls(urls)


    for url, content in zip(urls, results):

        print(f"URL: {url}\nContent Length: {len(content)}\n---\n")


In this example, we define an asynchronous function fetch_url that makes an HTTP request using the requests library and returns the HTML content of the URL. The scrape_urls function takes a list of URLs, creates a task for each URL, and uses asyncio.gather to await all the tasks concurrently.

The main function is the entry point, where we define the URLs to scrape and call the scrape_urls function. Finally, we print the URL and the length of the content for each URL.


By using asyncio and executing tasks concurrently, the web scraping process becomes faster as the requests are made concurrently instead of sequentially. This example demonstrates the power of concurrent programming and how it can be applied to perform complex tasks efficiently.

Note that this is just a simplified example, and in real-world scenarios, you may need to handle errors, implement rate limiting, or use more advanced techniques. Nonetheless, it gives you an idea of how to leverage concurrency and asynchronous operations in Python to tackle complex tasks.


As I mentioned, there are a lot of libraries for handling concurrency in Python, I mention some of them here:

  1. asyncio: The built-in library for asynchronous programming in Python. It provides an event loop and coroutines for managing concurrent operations.
  2. threading: The built-in module for creating and managing threads in Python. It allows you to run multiple threads concurrently.
  3. multiprocessing: The built-in module for multiprocessing in Python. It enables the execution of multiple processes in parallel.
  4. concurrent.futures: A module that provides a high-level interface for asynchronously executing functions using threads or processes. It includes the ThreadPoolExecutor and ProcessPoolExecutor classes.
  5. queue: The built-in module for implementing thread-safe queues. It is useful for communication and coordination between multiple threads.
  6. threadpool: A third-party library that provides a simple thread pool implementation for executing tasks in parallel using threads.
  7. joblib: A library that provides tools for parallel and distributed computing in Python. It supports both thread-based and process-based parallelism.
  8. rxpy: A reactive programming library for Python that allows you to handle asynchronous and concurrent operations using reactive streams.
  9. gevent: A coroutine-based concurrency library that provides a high-level synchronous API. It allows you to write concurrent programs using the familiar synchronous style of programming.


Category: Software

Tags: Python

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