Breaking circular reference between Actor and its ActorRef

src/pykka/_proxy.py

@@ -139,7 +139,10 @@ def __init__(
             msg = f"{actor_ref} not found"
             raise ActorDeadError(msg)
         self.actor_ref = actor_ref
-        self._actor = actor_ref._actor  # noqa: SLF001
+        self._actor = actor_ref._actor_weakref()  # noqa: SLF001
+        if self._actor is None:
+            msg = f"{actor_ref} not found (weakref has been deallocated)"
+            raise ActorDeadError(msg)
         self._attr_path = attr_path or ()
         self._known_attrs = introspect_attrs(root=self._actor, proxy=self)
         self._actor_proxies = {}

src/pykka/_ref.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import weakref
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -51,7 +52,7 @@ def __init__(
         self,
         actor: A,
     ) -> None:
-        self._actor = actor
+        self._actor_weakref = weakref.ref(actor)
         self.actor_class = actor.__class__
         self.actor_urn = actor.actor_urn
         self.actor_inbox = actor.actor_inbox