gh-121333: Clarify what is the default executor for asyncio.run_in_executor (#121335)

Co-authored-by: Kumar Aditya <kumaraditya@python.org>

diff --git a/Doc/library/asyncio-eventloop.rst b/Doc/library/asyncio-eventloop.rst
index 1d79f78e8e1b67934b1ac1223e10b8f7e6bda4a5..70bdd154d6c406db770702152d0d4ba15422095a 100644 (file)
--- a/Doc/library/asyncio-eventloop.rst
+++ b/Doc/library/asyncio-eventloop.rst
@@ -1262,6 +1262,9 @@ Executing code in thread or process pools
 
    The *executor* argument should be an :class:`concurrent.futures.Executor`
    instance. The default executor is used if *executor* is ``None``.
+   The default executor can be set by :meth:`loop.set_default_executor`,
+   otherwise, a :class:`concurrent.futures.ThreadPoolExecutor` will be
+   lazy-initialized and used by :func:`run_in_executor` if needed.
 
    Example::