Where is multithreading needed in Python and is it needed at all?

Multithreading in Python is useful when you need to perform multiple tasks simultaneously, especially if these tasks involve input/output (I/O), such as network requests, file handling, or database operations. Due to the GIL (Global Interpreter Lock) in the standard Python implementation (CPython), multithreading is inefficient for CPU-intensive tasks because threads cannot run in parallel on multiple cores.

Example of using multithreading for parallel network requests:

import threading
import requests

def fetch_url(url):
    response = requests.get(url)
    print(f"{url}: {len(response.content)} bytes")

urls = ["https://example.com", "https://python.org", "https://github.com"]
threads = []

for url in urls:
    thread = threading.Thread(target=fetch_url, args=(url,))
    thread.start()
    threads.append(thread)

for thread in threads:
    thread.join()

If the task is CPU-intensive, it is better to use multiprocessing or other approaches, as multithreading in Python is limited by the GIL.