2 files changed, 59 insertions, 0 deletions
diff --git a/Doc/library/asyncio-api-index.rst b/Doc/library/asyncio-api-index.rst
index d5b5659..047e5bb 100644
--- a/Doc/library/asyncio-api-index.rst
+++ b/Doc/library/asyncio-api-index.rst
@@ -48,6 +48,9 @@ await on multiple things with timeouts.
     * - :class:`Task`
       - Task object.
 
+    * - :func:`to_thread`
+      - Asychronously run a function in a separate OS thread.
+
     * - :func:`run_coroutine_threadsafe`
       - Schedule a coroutine from another OS thread.
 
diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst
index 2e96339..7c27040 100644
--- a/Doc/library/asyncio-task.rst
+++ b/Doc/library/asyncio-task.rst
@@ -602,6 +602,62 @@ Waiting Primitives
            # ...
 
 
+Running in Threads
+==================
+
+.. coroutinefunction:: to_thread(func, /, \*args, \*\*kwargs)
+
+   Asynchronously run function *func* in a separate thread.
+
+   Any \*args and \*\*kwargs supplied for this function are directly passed
+   to *func*.
+
+   Return an :class:`asyncio.Future` which represents 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
+   they were ran in the main thread. For example::
+
+       def blocking_io():
+           print(f"start blocking_io at {time.strftime('%X')}")
+           # Note that time.sleep() can be replaced with any blocking
+           # IO-bound operation, such as file operations.
+           time.sleep(1)
+           print(f"blocking_io complete at {time.strftime('%X')}")
+
+       async def main():
+           print(f"started main at {time.strftime('%X')}")
+
+           await asyncio.gather(
+               asyncio.to_thread(blocking_io),
+               asyncio.sleep(1))
+
+           print(f"finished main at {time.strftime('%X')}")
+
+
+       asyncio.run(main())
+
+       # Expected output:
+       #
+       # started main at 19:50:53
+       # start blocking_io at 19:50:53
+       # blocking_io complete at 19:50:54
+       # finished main at 19:50:54
+
+   Directly calling `blocking_io()` in any coroutine would block the event loop
+   for its duration, resulting in an additional 1 second of run time. Instead,
+   by using `asyncio.to_thread()`, we can run it in a separate thread without
+   blocking the event loop.
+
+   .. note::
+
+      Due to the :term:`GIL`, `asyncio.to_thread()` can typically only be used
+      to make IO-bound functions non-blocking. However, for extension modules
+      that release the GIL or alternative Python implementations that don't
+      have one, `asyncio.to_thread()` can also be used for CPU-bound functions.
+
+
 Scheduling From Other Threads
 =============================