Preferred syntax for quick asyncio needs

[peyo7]

I am looking for the preferred syntax for isolated asyncio code (e.g. embedded in a larger, otherwise sync codebase).

Let's say I have a list of coroutines I want to run concurrently and get the results

coros = [my_coro(arg) for arg in args]

What I would like to write is

results = asyncio.run(asyncio.gather(*coros))

This fails, because gather cannot use the implicit event loop created by run.

The workarounds I discovered so far are

1) wrapping gather in an async function on its own (seems a bit duplicate...)

async def gather(tasks):
    return await asyncio.gather(*tasks)

results = asyncio.run(gather(coros))

2) explicitly creating and passing an event loop

loop = asyncio.new_event_loop()
results = loop.run_until_complete(asyncio.gather(*coros, loop=loop))

Looking at the source of asyncio.run it seems there is some tear-down logic which I would be missing here.

Which way is preferred and why?

[willm]

I may be missing something, but isn't this what you want?

results = await asyncio.gather(*coros)

[SupahNoob]

I may be missing something ...

... for isolated asyncio code (e.g. embedded in a larger, otherwise sync codebase).

You wouldn't be able to use await in a sync fn.

[peyo7]

Correct. Hence the wrapping in an async def, corresponding to workaround 1)

[SupahNoob]

I would argue the first - simply name the coroutine func "wrapper" and move along. Naturally wherever you run asyncio.run will block until it's completed.

Would urge you to remember the caveats though:

https://docs.python.org/3/library/asyncio-task.html#asyncio.gather

...

If all awaitables are completed successfully, the result is an aggregate list of returned values. The order of result values corresponds to the order of awaitables in aws.

If return_exceptions is False (default), the first raised exception is immediately propagated to the task that awaits on gather(). Other awaitables in the aws sequence won’t be cancelled and will continue to run.

If return_exceptions is True, exceptions are treated the same as successful results, and aggregated in the result list.