How can I wrap a synchronous function in an async coroutine?
Eventually I found an answer in this thread. The method I was looking for is run_in_executor. This allows a synchronous function to be run asynchronously without blocking an event loop.
In the sleep
example I posted above, it might look like this:
import asynciofrom time import sleepasync def sleep_async(loop, delay): # None uses the default executor (ThreadPoolExecutor) await loop.run_in_executor(None, sleep, delay) return 'I slept asynchronously'
Also see the following answer -> How do we call a normal function where a coroutine is expected?
You can use a decorator to wrap the sync version to an async version.
import timefrom functools import wraps, partialdef wrap(func): @wraps(func) async def run(*args, loop=None, executor=None, **kwargs): if loop is None: loop = asyncio.get_event_loop() pfunc = partial(func, *args, **kwargs) return await loop.run_in_executor(executor, pfunc) return run@wrapdef sleep_async(delay): time.sleep(delay) return 'I slept asynchronously'
or use the aioify library
% pip install aioify
then
@aioifydef sleep_async(delay): pass
Maybe someone will need my solution to this problem. I wrote my own library to solve this, which allows you to make any function asynchronous using a decorator.
To install the library, run this command:
$ pip install awaits
To make any of your functions asynchronous, just add the @awaitable decorator to it, like this:
import timeimport asynciofrom awaits.awaitable import awaitable@awaitabledef sum(a, b): # heavy load simulation time.sleep(10) return a + b
Now you can make sure that your function is really asynchronous coroutine:
print(asyncio.run(sum(2, 2)))
"Under the hood" your function will be executed in the thread pool. This thread pool will not be recreated every time your function is called. A thread pool is created once and accepts new tasks via a queue. This will make your program run faster than using other solutions, because the creation of additional threads is an additional overhead.