How do I list files in Asyncio?

python, python-asyncio

Solution

Yes, I think that's the best way. There is no native non-blocking call to list files that I'm aware of, so you've got no choice but to run the blocking call in a thread/subprocess to get non-blockiing behavior. Here's a simple example using `ProcessPoolExecutor`.

import concurrent.futures
import asyncio
import os

def list_files():
    return os.listdir(".")

def on_got_files(fut):
   print("got files {}".format(fut.result()))
   loop.stop()


def main():
   with concurrent.futures.ProcessPoolExecutor() as executor:
       fut = loop.run_in_executor(executor, list_files)
       fut.add_done_callback(on_got_files)
       print("Listing files asynchronously")

if __name__ == "__main__":
   loop = asyncio.get_event_loop()
   loop.call_soon(main)
   loop.run_forever()

Output:

C:\Users\Dan\Desktop>python3 async.py
Listing files asynchronously
got files [<files are listed here>]

Problem

I want to be able to fetch a list of files without blocking, but i didn't see a way to do that in the documentation. Is the best way to do this in a executor?

Original source