Should We Use Multithreading or Async IO to Speed Up a Network Bound Task?

What will you learn?

In this tutorial, you will delve into the distinctions between multithreading and async IO in Python. You’ll gain insights into when to leverage each for enhancing the speed of network-bound tasks.

Introduction to the Problem and Solution

When confronted with a network-bound task in Python, the quest for performance enhancement often leads us to explore concurrency solutions. Two prevalent strategies for achieving concurrency in Python are multithreading and asyncio.

Multithreading involves executing multiple threads within the same process, while Async IO (Asynchronous I/O) revolves around an event loop that facilitates asynchronous programming. This exploration aims to determine the optimal approach for accelerating a network-bound task.


import threading
import asyncio

# Using Multithreading
def fetch_data(url):
    # Function to fetch data from a URL

urls = ['url1', 'url2', 'url3']

threads = []
for url in urls:
    thread = threading.Thread(target=fetch_data, args=(url,))

for thread in threads:

# Using Async IO
async def fetch_data_async(url):
    # Asynchronous function to fetch data from a URL

urls = ['url1', 'url2', 'url3']

async def main():
    tasks = [fetch_data_async(url) for url in urls]

    await asyncio.gather(*tasks)

# Copyright PHD


Multithreading vs Async IO:

  • Multithreading: Suitable for tasks involving blocking operations like network I/O as it enables other threads to continue execution.
  • Async IO: Ideal for I/O-bound tasks with waiting periods as it doesn’t block other operations during these intervals.

Choosing Between Them:

  • For network-bound tasks prioritizing latency, opt for Async IO due to its non-blocking nature.
  • If your task encompasses CPU-bound operations alongside I/O tasks, a hybrid approach combining both methods might yield superior outcomes.
    Which is more memory-efficient: multithreading or async io?

    Multithreading tends to consume more memory due to individual stack space per thread compared to async functions managed by an event loop.

    Can multithreading be used with async io together?

    Combining multithreading with async io can introduce complexity but is feasible depending on specific use cases.

    Does GIL (Global Interpreter Lock) affect either approach?

    Yes, GIL limits multi-core performance potential with CPython but may have less impact on async io due to its cooperative multitasking nature.

    When should I prefer synchronous code over these concurrent models?

    If your application isn’t heavily reliant on external resources like networks or databases, synchronous code may suffice without added complexity.

    How does error handling differ between multithreaded and asynchronous code?

    Error handling can be more intricate in multithreaded applications due to shared state concerns compared to the streamlined exception handling capabilities of asyncio.

    Is there any performance difference between them?

    Performance varies based on use case; generally, async io excels in high-latency scenarios while multithreading might perform better under conditions like CPU-intensive workloads alongside networking.

    Can we scale our application easily using these methods?

    Both techniques offer scalability benefits; however, effective application design leveraging their strengths necessitates tailored planning aligned with specific requirements.

    Are there any libraries that simplify working with these concepts further?

    Indeed. Libraries like aiohttp aid in constructing efficient web services using Async IO while concurrent.futures furnishes higher-level interfaces for managing concurrent executions within threads.


    Deciding between multithreading and async io hinges largely on your task’s nature: – Opt for Async IO for pure network-bound activities demanding low-latency responses or extensive waiting periods. – Consider judiciously combining both approaches if your workload entails CPU-intensive processing alongside networking requirements.

    Always profile your application’s performance before making conclusive decisions as real-world scenarios may present unique challenges not encompassed by general advice.

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