[docs] Update documentation for `multiprocessing.get_start_method` (GH-18170)

diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
index 8b76058bde04a84aa8f210442c1b10afad517666..c5d07dc5954842837977206431bdf14e2b207008 100644 (file)
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -1030,7 +1030,13 @@ Miscellaneous
 
    The return value can be ``'fork'``, ``'spawn'``, ``'forkserver'``
    or ``None``.  ``'fork'`` is the default on Unix, while ``'spawn'`` is
-   the default on Windows.
+   the default on Windows and macOS.
+
+.. versionchanged:: 3.8
+
+   On macOS, the *spawn* start method is now the default.  The *fork* start
+   method should be considered unsafe as it can lead to crashes of the
+   subprocess. See :issue:`33725`.
 
    .. versionadded:: 3.4