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Concurrency & performance

asyncio, threading, multiprocessing, and profiling-friendly performance patterns.

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Concurrency & performance medium

How to Demonstrate the GIL with Python Threads vs Processes

Measure and compare wall-clock time for CPU-bound work using Python threads (limited by the GIL) versus multiprocessing (which bypasses the GIL).

gil threading multiprocessing
Python 
import threading
import multiprocessing
import time
import os


def cpu_heavy(n):
    return sum(i * i for i in range(n))


def run_threads(n):
    threads = [threading.Thread(target=cpu_heavy, args=(n,)) for _ in range(2)]
    start = time.perf_counter()
    for t in threads:
        t.start()
    for t in threads:
 …
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