gh-135726: multiprocessing.freeze_support no longer sets the start method globally.

Lib/multiprocessing/context.py

@@ -266,6 +266,17 @@ def get_all_start_methods(self):
         )
         return start_method_names
 
+    def freeze_support(self):
+        '''Check whether this is a fake forked process in a frozen executable.
+        If so then run code specified by commandline and exit.
+        '''
+        start_method = self.get_start_method(allow_none=True)
+        if start_method is None:
+            start_method = self._default_context.get_start_method()
+        if start_method == 'spawn' and getattr(sys, 'frozen', False):
+            from .spawn import freeze_support
+            freeze_support()
+
 
 #
 # Context types for fixed start method

Misc/NEWS.d/next/Library/2025-06-22-15-42-10.gh-issue-135726._oO5IN.rst

@@ -0,0 +1,2 @@
+:func:`multiprocessing.freeze_support` no longer sets the start method
+globally.