New submission from James Barrett <james.barr...@bbc.co.uk>:

As discussed in < 
https://github.com/python/typeshed/issues/3999#issuecomment-634097968 > the 
type of `AbstractEventLoop.run_in_executor` is defined at < 
https://github.com/python/cpython/blob/master/Lib/asyncio/events.py#L286 > as 
follows:

```
async def run_in_executor(self, executor, func, *args):
        raise NotImplementedError
```

However all concrete implementations of this method are actually not async 
methods but rather synchronous methods which return a Future object.

Logically this appears to make sense: at base `run_in_executor` is not a 
coroutine, since it doesn't create an object representing code which will be 
executed when the object is awaited, rather it returns an object representing 
code which is running asynchronously elsewhere (on another thread) and which 
can be awaited to wait for that other thread to complete its task. Which seems 
to be a perfect match to what a Future object is supposed to be.

As such it seems that the current definition of the method as a coroutine is 
possibly a mistake.

Alternatively if some feel that it is important to allow concrete 
implementations to implement it as a coroutine if they need to then perhaps it 
could be specified to be a method returning an Awaitable, since that would 
cover both options?

----------
components: Library (Lib)
messages: 370005
nosy: jamesba
priority: normal
severity: normal
status: open
title: AbstactEventLoop.run_in_executor is listed as an async method, but 
should actually return a Futrue
type: behavior
versions: Python 3.10, Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python 
3.9

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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue40782>
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