Aiofutures

• General information
• Installation
• Usage
  • Implicit initialization (global executor)
  • Explicit initialization
  • UVLoop
  • Notes
• Contribution

General information

aiofutures provides tools to integrate an asynchronous code into your synchronous application in a usual and easy way using standard library's concurrent.futures.Executor interface.

It may be useful when you want to:

• smoothly migrate your synchronous codebase to asynchronous style
• decrease a number of threads in your application

Replace this:

from concurrent.futures import ThreadPoolExecutor

with ThreadPoolExecutor() as ex:
    future = ex.submit(sync_task)
    result = future.result()

With this:

from aiofutures import AsyncExecutor

with AsyncExecutor() as ex:
    future = ex.submit(async_task)
    result = future.result()

The former spawns a lot of threads and experiences all cons of GIL, the latter spawns the only one async thread (check out notes)

Installation

You can install aiofutures using pip:

pip install aiofutures

Usage

Implicit initialization (global executor)

Set an environment variable AIOFUTURES_INIT to any value and use shortcuts from the library:

os.environ.setdefault('AIOFUTURES_INIT', '1')

from aiofutures import run_async

async def io_bound_task(seconds):
    await asyncio.sleep(seconds)
    return seconds

future = run_async(io_bound_task, 5)
print(future.result())

AIOFUTURES_INIT implicitly initializes a global AsyncExecutor and gives you an option to use shortcuts run_async and sync_to_async.

Explicit initialization

Use an instance of the AsyncExecutor directly:

from aiofutures import AsyncExecutor

executor = AsyncExecutor()
future = executor.submit(io_bound_task, 5)
print(future.result())

In cases when you need to do IO synchronously within async tasks, you can use sync_to_async:

from aiofutures import AsyncExecutor, sync_to_async

executor = AsyncExecutor()

async def io_bound_task():
    # or with the shortcut
    # url = await sync_to_async(fetch_url_from_db_sync)
    url = await executor.sync_to_async(fetch_url_from_db_sync)
    data = await fetch_data(url)
    return data

future = executor.submit(io_bound_task)
print(future.result())

NOTE: You can use sync_to_async within tasks running in the executor only.

UVLoop

To use with the high performance uvloop install it before initialization:

# install before the import for the global executor
import uvloop
uvloop.install()
from aiofutures import run_async
...

# or before an explicit initialization
import uvloop
from aiofutures import AsyncExecutor
uvloop.install()
executor = AsyncExecutor()

Notes

• Take into account that asyncio still (CPython3.11) resolves DNS in threads, not asynchronously
• Any blocking function will block the whole AsyncExecutor

Contribution

All suggestions are welcome!