bpo-32309: Add support for contextvars in asyncio.to_thread() (GH-20278)
Allows contextvars from the main thread to be accessed in the separate thread used in `asyncio.to_thread()`. See the [discussion](https://github.com/python/cpython/pull/20143GH-discussion_r427808225) in GH-20143 for context.
Automerge-Triggered-By: @aeros
(cherry picked from commit 0f56263e62ba91d0baae40fb98947a3a98034a73)
Co-authored-by: Kyle Stanley <aeros167@gmail.com>
diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst
index 7c27040..dd94c14 100644
--- a/Doc/library/asyncio-task.rst
+++ b/Doc/library/asyncio-task.rst
@@ -610,7 +610,9 @@
Asynchronously run function *func* in a separate thread.
Any \*args and \*\*kwargs supplied for this function are directly passed
- to *func*.
+ to *func*. Also, the current :class:`contextvars.Context` is propogated,
+ 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*.
@@ -657,6 +659,8 @@
that release the GIL or alternative Python implementations that don't
have one, `asyncio.to_thread()` can also be used for CPU-bound functions.
+ .. versionadded:: 3.9
+
Scheduling From Other Threads
=============================