diff --git a/heat/engine/service.py b/heat/engine/service.py
index b46994cf83..c22a0001f5 100644
--- a/heat/engine/service.py
+++ b/heat/engine/service.py
@@ -368,6 +368,7 @@ class EngineService(service.Service):
         self._client = rpc_messaging.get_rpc_client(
             version=self.RPC_API_VERSION)
 
+        self._configure_db_conn_pool_size()
         self.service_manage_cleanup()
         self.manage_thread_grp = threadgroup.ThreadGroup()
         self.manage_thread_grp.add_timer(cfg.CONF.periodic_interval,
@@ -376,6 +377,18 @@ class EngineService(service.Service):
 
         super(EngineService, self).start()
 
+    def _configure_db_conn_pool_size(self):
+        # bug #1491185
+        # Set the DB max_overflow to match the thread pool size.
+        # The overflow connections are automatically closed when they are
+        # not used; setting it is better than setting DB max_pool_size.
+        worker_pool_size = cfg.CONF.executor_thread_pool_size
+        # Update max_overflow only if it is not adequate
+        if ((cfg.CONF.database.max_overflow is None) or
+                (cfg.CONF.database.max_overflow < worker_pool_size)):
+            cfg.CONF.set_override('max_overflow', worker_pool_size,
+                                  group='database')
+
     def _stop_rpc_server(self):
         # Stop rpc connection at first for preventing new requests
         LOG.debug("Attempting to stop engine service...")
diff --git a/heat/tests/engine/service/test_service_engine.py b/heat/tests/engine/service/test_service_engine.py
index 908a1cb929..18f338cfdd 100644
--- a/heat/tests/engine/service/test_service_engine.py
+++ b/heat/tests/engine/service/test_service_engine.py
@@ -230,8 +230,10 @@ class ServiceEngineTest(common.HeatTestCase):
                 return_value=mock.Mock())
     @mock.patch('oslo_service.threadgroup.ThreadGroup',
                 return_value=mock.Mock())
+    @mock.patch.object(service.EngineService, '_configure_db_conn_pool_size')
     def test_engine_service_start_in_non_convergence_mode(
             self,
+            configure_db_conn_pool_size,
             thread_group_class,
             engine_listener_class,
             thread_group_manager_class,
@@ -267,8 +269,10 @@ class ServiceEngineTest(common.HeatTestCase):
                 return_value=mock.Mock())
     @mock.patch('oslo_service.threadgroup.ThreadGroup',
                 return_value=mock.Mock())
+    @mock.patch.object(service.EngineService, '_configure_db_conn_pool_size')
     def test_engine_service_start_in_convergence_mode(
             self,
+            configure_db_conn_pool_size,
             thread_group_class,
             worker_service_class,
             engine_listener_class,
@@ -380,3 +384,30 @@ class ServiceEngineTest(common.HeatTestCase):
     def test_engine_service_reset(self, setup_logging_mock):
         self.eng.reset()
         setup_logging_mock.assert_called_once_with(cfg.CONF, 'heat')
+
+    @mock.patch('oslo_messaging.Target',
+                return_value=mock.Mock())
+    @mock.patch('heat.common.messaging.get_rpc_client',
+                return_value=mock.Mock())
+    @mock.patch('heat.engine.stack_lock.StackLock.generate_engine_id',
+                return_value=mock.Mock())
+    @mock.patch('heat.engine.service.ThreadGroupManager',
+                return_value=mock.Mock())
+    @mock.patch('heat.engine.service.EngineListener',
+                return_value=mock.Mock())
+    @mock.patch('heat.engine.worker.WorkerService',
+                return_value=mock.Mock())
+    @mock.patch('oslo_service.threadgroup.ThreadGroup',
+                return_value=mock.Mock())
+    def test_engine_service_configures_connection_pool(
+            self,
+            thread_group_class,
+            worker_service_class,
+            engine_listener_class,
+            thread_group_manager_class,
+            sample_uuid_method,
+            rpc_client_class,
+            target_class):
+        self.eng.start()
+        self.assertEqual(cfg.CONF.executor_thread_pool_size,
+                         cfg.CONF.database.max_overflow)