Python: Run only one function async - asynchronous

Question

I have a large legacy application that has one function that is a prime candidate to be executed async. It's IO bound (network and disk) and doesn't return anything.
This is a very simple similar implementation:
import random
import time
import requests
def fetch_urls(site):
wait = random.randint(0, 5)
filename = site.split("/")[2].replace(".", "_")
print(f"Will fetch {site} in {wait} seconds")
time.sleep(wait)
r = requests.get(site)
with open(filename, "w") as fd:
fd.write(r.text)
def something(sites):
for site in sites:
fetch_urls(site)
return True
def main():
sites = ["https://www.google.com", "https://www.reddit.com", "https://www.msn.com"]
start = time.perf_counter()
something(sites)
total_time = time.perf_counter() - start
print(f"Finished in {total_time}")
if __name__ == "__main__":
main()
My end goal would be updating the something function to run fetch_urls async.
I cannot change fetch_urls.
All documentation and tutorials I can find assumes my entire application is async (starting from async def main()) but this is not the case.
It's a huge application spanning across multiple modules and re-factoring everything for a single function doesn't look right.
For what I understand I will need to create a loop, add tasks to it and dispatch it somehow, but I tried many different things and I still get everything running just one after another - as oppose to concurrently.
I would appreciate any assistance. Thanks!

Answer 1

Replying to myself, it seems there is no easy way to do that with async. Ended up using concurrent.futures
import time
import requests
import concurrent.futures
def fetch_urls(url, name):
wait = 5
filename = url.split("/")[2].replace(".", "_")
print(f"Will fetch {name} in {wait} seconds")
time.sleep(wait)
r = requests.get(url)
with open(filename, "w") as fd:
fd.write(r.text)
def something(sites):
with concurrent.futures.ProcessPoolExecutor(max_workers=5) as executor:
future_to_url = {
executor.submit(fetch_urls, url["url"], url["name"]): (url)
for url in sites["children"]
}
for future in concurrent.futures.as_completed(future_to_url):
url = future_to_url[future]
try:
data = future.result()
except Exception as exc:
print("%r generated an exception: %s" % (url, exc))
return True
def main():
sites = {
"parent": "https://stackoverflow.com",
"children": [
{"name": "google", "url": "https://google.com"},
{"name": "reddit", "url": "https://reddit.com"},
],
}
start = time.perf_counter()
something(sites)
total_time = time.perf_counter() - start
print(f"Finished in {total_time}")