Example showing asynchronous HTTP request with Python 3.5.0 + asyncio

asynchronous_example.py

import requests
import asyncio
from concurrent.futures import ThreadPoolExecutor
from timeit import default_timer

START_TIME = default_timer()

def fetch(session, csv):
    base_url = "https://people.sc.fsu.edu/~jburkardt/data/csv/"
    with session.get(base_url + csv) as response:
        data = response.text
        if response.status_code != 200:
            print("FAILURE::{0}".format(url))

        elapsed = default_timer() - START_TIME
        time_completed_at = "{:5.2f}s".format(elapsed)
        print("{0:<30} {1:>20}".format(csv, time_completed_at))

        return data

async def get_data_asynchronous():
    csvs_to_fetch = [
        "ford_escort.csv",
        "cities.csv",
        "hw_25000.csv",
        "mlb_teams_2012.csv",
        "nile.csv",
        "homes.csv",
        "hooke.csv",
        "lead_shot.csv",
        "news_decline.csv",
        "snakes_count_10000.csv",
        "trees.csv",
        "zillow.csv"
    ]
    print("{0:<30} {1:>20}".format("File", "Completed at"))
    with ThreadPoolExecutor(max_workers=10) as executor:
        with requests.Session() as session:
            # Set any session parameters here before calling `fetch`
            loop = asyncio.get_event_loop()
            START_TIME = default_timer()
            tasks = [
                loop.run_in_executor(
                    executor,
                    fetch,
                    *(session, csv) # Allows us to pass in multiple arguments to `fetch`
                )
                for csv in csvs_to_fetch
            ]
            for response in await asyncio.gather(*tasks):
                pass

def main():
    loop = asyncio.get_event_loop()
    future = asyncio.ensure_future(get_data_asynchronous())
    loop.run_until_complete(future)

main()

Is there some memory leaks in this code ?

There shouldn't be, if you are referring to https://bugs.python.org/issue38430. We want to make a list of Futures (line 42) so that we can kick off each process asynchronously. We use await on line 50 when getting the results of each task.

If you do have any data to show that this leaks memory I'm happy to help pin it down!