diff --git a/taskflow/engines/action_engine/analyzer.py b/taskflow/engines/action_engine/analyzer.py
index f5c68722..78d4c29f 100644
--- a/taskflow/engines/action_engine/analyzer.py
+++ b/taskflow/engines/action_engine/analyzer.py
@@ -15,8 +15,8 @@
 #    under the License.
 
 import abc
-import functools
 import itertools
+import weakref
 
 from networkx.algorithms import traversal
 import six
@@ -101,12 +101,9 @@ class Analyzer(object):
     """
 
     def __init__(self, runtime):
+        self._runtime = weakref.proxy(runtime)
         self._storage = runtime.storage
         self._execution_graph = runtime.compilation.execution_graph
-        self._check_atom_transition = runtime.check_atom_transition
-        self._fetch_edge_deciders = runtime.fetch_edge_deciders
-        self._fetch_retries = functools.partial(
-            runtime.fetch_atoms_by_kind, 'retry')
 
     def get_next_nodes(self, node=None):
         """Get next nodes to run (originating from node or all nodes)."""
@@ -174,7 +171,8 @@ class Analyzer(object):
 
         state = self.get_state(atom)
         intention = self._storage.get_atom_intention(atom.name)
-        transition = self._check_atom_transition(atom, state, st.RUNNING)
+        transition = self._runtime.check_atom_transition(atom, state,
+                                                         st.RUNNING)
         if not transition or intention != st.EXECUTE:
             return (False, None)
 
@@ -190,7 +188,7 @@ class Analyzer(object):
         if not ok_to_run:
             return (False, None)
         else:
-            edge_deciders = self._fetch_edge_deciders(atom)
+            edge_deciders = self._runtime.fetch_edge_deciders(atom)
             return (True, IgnoreDecider(atom, edge_deciders))
 
     def _get_maybe_ready_for_revert(self, atom):
@@ -198,7 +196,8 @@ class Analyzer(object):
 
         state = self.get_state(atom)
         intention = self._storage.get_atom_intention(atom.name)
-        transition = self._check_atom_transition(atom, state, st.REVERTING)
+        transition = self._runtime.check_atom_transition(atom, state,
+                                                         st.REVERTING)
         if not transition or intention not in (st.REVERT, st.RETRY):
             return (False, None)
 
@@ -226,7 +225,7 @@ class Analyzer(object):
 
         If no state is provided it will yield back all retry atoms.
         """
-        for atom in self._fetch_retries():
+        for atom in self._runtime.fetch_atoms_by_kind('retry'):
             if not state or self.get_state(atom) == state:
                 yield atom
 
diff --git a/taskflow/engines/action_engine/builder.py b/taskflow/engines/action_engine/builder.py
index f46d4a1f..9ab26d4a 100644
--- a/taskflow/engines/action_engine/builder.py
+++ b/taskflow/engines/action_engine/builder.py
@@ -14,6 +14,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import weakref
 
 from automaton import machines
 
@@ -91,7 +92,7 @@ class MachineBuilder(object):
     """
 
     def __init__(self, runtime, waiter):
-        self._runtime = runtime
+        self._runtime = weakref.proxy(runtime)
         self._analyzer = runtime.analyzer
         self._completer = runtime.completer
         self._scheduler = runtime.scheduler
diff --git a/taskflow/engines/action_engine/scheduler.py b/taskflow/engines/action_engine/scheduler.py
index 404781e6..5fdc1995 100644
--- a/taskflow/engines/action_engine/scheduler.py
+++ b/taskflow/engines/action_engine/scheduler.py
@@ -76,7 +76,7 @@ class Scheduler(object):
     """Safely schedules atoms using a runtime ``fetch_scheduler`` routine."""
 
     def __init__(self, runtime):
-        self._fetch_scheduler = runtime.fetch_scheduler
+        self._runtime = weakref.proxy(runtime)
 
     def schedule(self, atoms):
         """Schedules the provided atoms for *future* completion.
@@ -89,7 +89,7 @@ class Scheduler(object):
         """
         futures = set()
         for atom in atoms:
-            scheduler = self._fetch_scheduler(atom)
+            scheduler = self._runtime.fetch_scheduler(atom)
             try:
                 futures.add(scheduler.schedule(atom))
             except Exception: