fix: opening a moc from a pickle now increments the number of refs to…

… the object in store

CHANGELOG.md

@@ -20,6 +20,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * `MOC.border` no does not attempt on plotting the border when the MOc is out of the
 view anymore.
+* fix an issue where the number of references to the rust side was not
+incremented when a moc was created from a pickle file. This also solves a lot of issues
+with the multiprocessing module that calls pickle behind the scenes.
 
 ### Added
 

python/mocpy/abstract_moc.py

@@ -51,6 +51,12 @@ def __copy__(self):
     def __deepcopy__(self, memo):
         return self.__copy__()
 
+    def __setstate__(self, state):
+        # this is called when a MOC is unpickled
+        # we create a new ref count with copy
+        mocpy.copy(state["store_index"])
+        self.__dict__ = state
+
     @staticmethod
     def _store_index_dtype():
         """Store the datatype of the index.