[3.13] gh-153141: Fix mutable default argument in _SharedMemoryTracker.__init__ (GH-153142) (#153147)

miss-islington · whyvineet · web-flow · commit e9f8969cf2fb · 2026-07-05T12:36:15.000-07:00
gh-153141: Fix mutable default argument in _SharedMemoryTracker.__init__ (GH-153142) Fix default argument for segment_names in _SharedMemoryTracker constructor to not use a mutable list. (cherry picked from commit d733b10) Co-authored-by: Vineet Kumar <108144301+whyvineet@users.noreply.github.com>
diff --git a/Lib/multiprocessing/managers.py b/Lib/multiprocessing/managers.py
@@ -1253,9 +1253,9 @@ class SyncManager(BaseManager):
     class _SharedMemoryTracker:
         "Manages one or more shared memory segments."
 
-        def __init__(self, name, segment_names=[]):
+        def __init__(self, name, segment_names=None):
             self.shared_memory_context_name = name
-            self.segment_names = segment_names
+            self.segment_names = [] if segment_names is None else segment_names
 
         def register_segment(self, segment_name):
             "Adds the supplied shared memory block name to tracker."
