FIX: squash memory leak for redraws

jklymak · jklymak · commit 2f0a96cbbb87 · 2018-08-29T16:03:35.000-07:00
diff --git a/lib/matplotlib/transforms.py b/lib/matplotlib/transforms.py
@@ -169,7 +169,13 @@ def set_children(self, *children):
         # parents are destroyed, references from the children won't
         # keep them alive.
         for child in children:
-            child._parents[id(self)] = weakref.ref(self)
+            # pass a weak reference.  The second arg is a callback for
+            # when the weak ref is garbage collected to also
+            # remove the dictionary element, otherwise child._parents
+            # keeps growing for multiple draws.
+            ref = weakref.ref(self, lambda ref, sid=id(self),
+                                        target=child._parents: target.pop(sid))
+            child._parents[id(self)] = ref
 
     if DEBUG:
         _set_children = set_children
