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Concurrency & performance

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

4 matches

How to Run Coroutines Concurrently with asyncio.gather in Python

Run multiple async coroutines concurrently and collect their results in the order they were passed.

import asyncio


async def fetch_data(name: str, delay: float) -> str:
    """Simulate an async operation (e.g., API call) with a delay."""
    await asyncio.sleep(delay)
    return f"{name} data (after {delay}s)"


async def main() -> None:
    """Run multiple coroutines concurrently with asyncio.gather."""
    resul…

14 0 Open

Concurrency & performance medium

How to Use asyncio Lock to Protect a Shared Counter in Python

This code demonstrates how to use an asyncio.Lock to safely increment a shared counter from multiple concurrent coroutines.

asyncio lock concurrency

Python

import asyncio

async def increment(counter, lock, increments):
    for _ in range(increments):
        async with lock:
            counter[0] += 1

async def main():
    counter = [0]
    lock = asyncio.Lock()
    tasks = [
        increment(counter, lock, 1000)
        for _ in range(5)
    ]
    await asyncio.gath…

16 0 Open

Concurrency & performance medium

Limit Concurrency with asyncio.Semaphore in Python

Use asyncio.Semaphore to cap how many async tasks run at once, throttling a batch of coroutines to a set concurrency limit.

asyncio concurrency semaphore

Python

import asyncio
import random


async def fetch_data(i: int, semaphore: asyncio.Semaphore) -> str:
    async with semaphore:
        print(f"Task {i} starts")
        await asyncio.sleep(random.uniform(0.1, 0.5))
        print(f"Task {i} finishes")
        return f"Result {i}"


async def main() -> None:
    semaphore …

13 0 Open

Concurrency & performance medium

asyncio Condition wait notify pattern in Python

Coordinate coroutines with asyncio.Condition: workers wait for notifications and the main task notifies one or all of them.

asyncio concurrency synchronization

Python

import asyncio


async def worker(condition, name):
    async with condition:
        print(f"{name} waiting...")
        await condition.wait()
        print(f"{name} notified!")


async def main():
    condition = asyncio.Condition()
    tasks = [asyncio.create_task(worker(condition, f"worker-{i}")) for i in range(3…

14 0 Open

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