What's New + issue ref fix.

Author: gpshead

Doc/library/multiprocessing.rst

@@ -168,7 +168,7 @@ to start a process.  These *start methods* are
 
    On POSIX platforms the default start method was changed from *fork* to
    *forkserver* to retain the performance but avoid common multithreaded
-   process incompatibilities. See :issue:`84559`.
+   process incompatibilities. See :gh:`84559`.
 
 
 On POSIX using the *spawn* or *forkserver* start methods will also

Doc/whatsnew/3.14.rst

@@ -367,6 +367,14 @@ Deprecated
   as a single positional argument.
   (Contributed by Serhiy Storchaka in :gh:`109218`.)
 
+* :mod:`multiprocessing` and :mod:`concurrent.futures`:
+  The default start method (see :ref:`multiprocessing-start-methods`) changed
+  away from *fork* to *forkserver* on platforms where it was not already
+  *spawn* (Windows & macOS). If you require the threading incompatible *fork*
+  start method you must explicitly specify it when using :mod:`multiprocessing`
+  or :mod:`concurrent.futures` APIs.
+  (Contributed by Gregory P. Smith in :gh:`84559`.)
+
 * :mod:`os`:
   :term:`Soft deprecate <soft deprecated>` :func:`os.popen` and
   :func:`os.spawn* <os.spawnl>` functions. They should no longer be used to