From 2b201369b435a4266bda5b895e3b615dbe28ea6e Mon Sep 17 00:00:00 2001 From: Kyle Stanley Date: Sun, 31 May 2020 03:07:04 -0400 Subject: [PATCH] Fix asyncio.to_thread() documented return type (GH-20547) When I wrote the documentation for `asyncio.to_thread()`, I mistakenly assumed that `return await loop.run_in_executor(...)` within an async def function would return a Future. In reality, it returns a coroutine. This likely won't affect typical usage of `asyncio.to_thread()`, but it's important for the documentation to be correct here. In general, we also tend to avoid returning futures from high-level APIs in asyncio. --- Doc/library/asyncio-task.rst | 3 +-- Lib/asyncio/threads.py | 2 +- 2 files changed, 2 insertions(+), 3 deletions(-) diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst index 847363b134a..21824ca537f 100644 --- a/Doc/library/asyncio-task.rst +++ b/Doc/library/asyncio-task.rst @@ -614,8 +614,7 @@ Running in Threads allowing context variables from the event loop thread to be accessed in the separate thread. - Return an :class:`asyncio.Future` which represents the eventual result of - *func*. + Return a coroutine that can be awaited to get the eventual result of *func*. This coroutine function is primarily intended to be used for executing IO-bound functions/methods that would otherwise block the event loop if diff --git a/Lib/asyncio/threads.py b/Lib/asyncio/threads.py index 51e0ba95d82..34b7513a420 100644 --- a/Lib/asyncio/threads.py +++ b/Lib/asyncio/threads.py @@ -17,7 +17,7 @@ async def to_thread(func, /, *args, **kwargs): allowing context variables from the main thread to be accessed in the separate thread. - Return an asyncio.Future which represents the eventual result of *func*. + Return a coroutine that can be awaited to get the eventual result of *func*. """ loop = events.get_running_loop() ctx = contextvars.copy_context()