asyncio.gather tracing produces nested spans

[vmarkovtsev]

I've got the following code:

import asyncio
import sentry_sdk

async def foo():
    with sentry_sdk.start_span(op="foo"):
        await asyncio.sleep(1)

async def bar():
    with sentry_sdk.start_span(op="bar"):
        await asyncio.sleep(1)

with sentry_sdk.start_span(op="root"):
    await asyncio.gather(foo(), bar(), return_exceptions=True)

I see that bar is nested under foo, and foo is nested under root in the Performance UI.

root
    |- foo
         |- bar

Expected behavior: both foo and bar are nested under root and are on the same level.

root
    |- foo
    |- bar

[untitaker]

yes, our asyncio support is somewhat limited at the moment. As a workaround you can do:

import asyncio
import sentry_sdk

async def foo():
    with sentry_sdk.Hub(sentry_sdk.Hub.current):
        with sentry_sdk.start_span(op="foo"):
            await asyncio.sleep(1)

async def bar():
    with sentry_sdk.Hub(sentry_sdk.Hub.current):
        with sentry_sdk.start_span(op="bar"):
            await asyncio.sleep(1)

with sentry_sdk.start_span(op="root"):
    await asyncio.gather(asyncio.create_task(foo()), asyncio.create_task(bar()), return_exceptions=True)

I am not sure if create_task is strictly necessary or if gather does that for you. If gather already creates independent tasks then we can potentially handle this case transparently.

[vmarkovtsev]

Yes, asyncio.gather launches new Task-s, via https://docs.python.org/3/library/asyncio-task.html#asyncio.gather

If any awaitable in aws is a coroutine, it is automatically scheduled as a Task.

All right, thanks for the workaround!

[yoav-orca]

@untitaker do you have any plans to add this as first-class support? we are heavy users of this asyncio and this creates unreadable traces

[untitaker]

@yoav-orca not at the moment. It would also require heavy monkeypatching of the asyncio runtime afaik

[sl0thentr0py]

We're currently looking into this and as far as I can tell we can tell asyncio to use a custom task factory which will wrap all tasks with hub cloning and that should fix this issue.

https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.set_task_factory

We just have to be careful to take into account if there's another factory override and be good citizens on our end in both cases (default/existing custom factory).

[antonpirker]

I have now created a reproduction repo: https://github.com/getsentry/minimum_python_async/blob/main/task1.py

And I created a new AsyncioIntegration that produces now this output:

Which is the output we want to have :)