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Concurrency & performance

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

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Concurrency & performance medium

How to Use as_completed to Process Futures in Order of Completion

Submit multiple tasks to a ThreadPoolExecutor and process each result as soon as it finishes using as_completed.

concurrency threads futures
Python 
from concurrent.futures import ThreadPoolExecutor, as_completed
import time


def fetch_data(item_id):
    time.sleep(1)
    return f"item-{item_id}"


def main():
    with ThreadPoolExecutor(max_workers=3) as executor:
        future_map = {executor.submit(fetch_data, i): i for i in range(1, 6)}
        for future in…
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