SynchronizedBase isn't as helpful as I thought.

Author: distortedsignal

Lib/multiprocessing/sharedctypes.py

@@ -16,7 +16,16 @@
 from .context import reduction, assert_spawning
 _ForkingPickler = reduction.ForkingPickler
 
-__all__ = ['RawValue', 'RawArray', 'Value', 'Array', 'copy', 'synchronized', 'SynchronizedBase']
+__all__ = [
+    # Methods for getting ctypes in shared memory
+    'RawValue', 'RawArray',
+    # Methods for getting synchronization wrappers
+    'Value', 'Array',
+    # The synchronization types
+    'Synchronized', 'SynchronizedArray', 'SynchronizedString',
+    # Misc functions
+    'copy', 'synchronized'
+]
 
 #
 #

Misc/NEWS.d/next/Documentation/2023-10-03-17-59-00.gh-issue-0.m1D01N.rst

@@ -1,2 +1,4 @@
-Export :class:`multiprocessing.SynchronizedBase` so multiprocessing users can
-typecheck their code.
+Export :class:`multiprocessing.Synchronized`,
+:class:`multiprocessing.SynchronizedArray`, and
+:class:`multiprocessing.SynchronizedString` so multiprocessing users can
+annotate their code well.