diff --git a/heat/db/sqlalchemy/api.py b/heat/db/sqlalchemy/api.py
index dfdbcde005..fd7cb9ad8b 100644
--- a/heat/db/sqlalchemy/api.py
+++ b/heat/db/sqlalchemy/api.py
@@ -802,8 +802,13 @@ def stack_delete(context, stack_id):
         delete_softly(context, s)
 
 
+def _is_duplicate_error(exc):
+    return isinstance(exc, db_exception.DBDuplicateEntry)
+
+
 @oslo_db_api.wrap_db_retry(max_retries=3, retry_on_deadlock=True,
-                           retry_interval=0.5, inc_retry_interval=True)
+                           retry_interval=0.5, inc_retry_interval=True,
+                           exception_checker=_is_duplicate_error)
 def stack_lock_create(context, stack_id, engine_id):
     with db_context.writer.independent.using(context) as session:
         lock = session.query(models.StackLock).get(stack_id)
diff --git a/heat/engine/service.py b/heat/engine/service.py
index fb94cb6b62..f0929a1355 100644
--- a/heat/engine/service.py
+++ b/heat/engine/service.py
@@ -2449,15 +2449,17 @@ class EngineService(service.ServiceBase):
                 service_objects.Service.delete(cnxt, service_ref['id'])
 
     def reset_stack_status(self):
-        cnxt = context.get_admin_context()
         filters = {
             'status': parser.Stack.IN_PROGRESS,
             'convergence': False
         }
-        stacks = stack_object.Stack.get_all(cnxt,
+        stacks = stack_object.Stack.get_all(context.get_admin_context(),
                                             filters=filters,
                                             show_nested=True)
         for s in stacks:
+            # Build one context per stack, so that it can safely be passed to
+            # to thread.
+            cnxt = context.get_admin_context()
             stack_id = s.id
             lock = stack_lock.StackLock(cnxt, stack_id, self.engine_id)
             engine_id = lock.get_engine_id()
diff --git a/heat/tests/test_engine_service.py b/heat/tests/test_engine_service.py
index 743e97e059..854979c272 100644
--- a/heat/tests/test_engine_service.py
+++ b/heat/tests/test_engine_service.py
@@ -1328,7 +1328,7 @@ class StackServiceTest(common.HeatTestCase):
 
         self.eng.reset_stack_status()
 
-        mock_admin_context.assert_called_once_with()
+        mock_admin_context.assert_called()
         filters = {
             'status': parser.Stack.IN_PROGRESS,
             'convergence': False