diff --git a/qinling/api/controllers/v1/execution.py b/qinling/api/controllers/v1/execution.py
index dffaa0d7..7a923450 100644
--- a/qinling/api/controllers/v1/execution.py
+++ b/qinling/api/controllers/v1/execution.py
@@ -46,33 +46,39 @@ class ExecutionsController(rest.RestController):
 
         function_id = params['function_id']
         is_sync = params.get('sync', True)
+        func_url = None
 
-        # Check if the service url is existing.
-        try:
-            mapping = db_api.get_function_service_mapping(function_id)
-            LOG.debug('Found Service url for function: %s', function_id)
+        with db_api.transaction():
+            func_db = db_api.get_function(function_id)
 
-            func_url = '%s/execute' % mapping.service_url
-            LOG.info('Invoke function %s, url: %s', function_id, func_url)
+            # Increase function invoke count, the updated_at field will be also
+            # updated.
+            func_db.count = func_db.count + 1
+
+            try:
+                # Check if the service url is existing.
+                mapping_db = db_api.get_function_service_mapping(function_id)
+                LOG.info('Found Service url for function: %s', function_id)
+
+                func_url = '%s/execute' % mapping_db.service_url
+                LOG.info('Invoke function %s, url: %s', function_id, func_url)
+            except exc.DBEntityNotFoundError:
+                pass
+
+            if func_url:
+                r = requests.post(func_url, data=params.get('input'))
+                params.update(
+                    {'status': 'success', 'output': {'result': r.json()}}
+                )
+            else:
+                runtime_id = func_db.runtime_id
+                params.update({'status': 'running'})
 
-            r = requests.post(func_url, data=params.get('input'))
-            params.update(
-                {'status': 'success', 'output': {'result': r.json()}}
-            )
             db_model = db_api.create_execution(params)
 
-            return resources.Execution.from_dict(db_model.to_dict())
-        except exc.DBEntityNotFoundError:
-            pass
-
-        func = db_api.get_function(function_id)
-        runtime_id = func.runtime_id
-        params.update({'status': 'running'})
-
-        db_model = db_api.create_execution(params)
-
         self.engine_client.create_execution(
-            db_model.id, function_id, runtime_id, input=params.get('input'),
+            db_model.id, function_id, runtime_id,
+            input=params.get('input'),
             is_sync=is_sync
         )
 
diff --git a/qinling/api/controllers/v1/function.py b/qinling/api/controllers/v1/function.py
index ae23487a..2ab5abf1 100644
--- a/qinling/api/controllers/v1/function.py
+++ b/qinling/api/controllers/v1/function.py
@@ -177,7 +177,9 @@ class FunctionsController(rest.RestController):
             if source == 'package':
                 self.storage_provider.delete(context.get_ctx().projectid, id)
             if source == 'image':
-                self.engine_client.delete_function(id, func_db.name)
+                # If it's image function, need to delete all resources created
+                # by orchestrator asynchronously.
+                self.engine_client.delete_function(id)
 
             # This will also delete function service mapping as well.
             db_api.delete_function(id)
diff --git a/qinling/api/controllers/v1/resources.py b/qinling/api/controllers/v1/resources.py
index 83171a57..2ba30221 100644
--- a/qinling/api/controllers/v1/resources.py
+++ b/qinling/api/controllers/v1/resources.py
@@ -169,6 +169,7 @@ class Function(Resource):
     runtime_id = types.uuid
     code = types.jsontype
     entry = wtypes.text
+    count = int
     created_at = wtypes.text
     updated_at = wtypes.text
 
@@ -183,6 +184,7 @@ class Function(Resource):
             runtime_id='123e4567-e89b-12d3-a456-426655440001',
             code={'zip': True},
             entry='main',
+            count=10,
             created_at='1970-01-01T00:00:00.000000',
             updated_at='1970-01-01T00:00:00.000000'
         )
diff --git a/qinling/config.py b/qinling/config.py
index b69efa86..367e9bc0 100644
--- a/qinling/config.py
+++ b/qinling/config.py
@@ -91,6 +91,11 @@ engine_opts = [
         choices=['kubernetes', 'swarm'],
         help='The container orchestrator.'
     ),
+    cfg.IntOpt(
+        'function_service_expiration',
+        default=300,
+        help='Maximum service time for function in orchestrator.'
+    )
 ]
 
 STORAGE_GROUP = 'storage'
diff --git a/qinling/db/api.py b/qinling/db/api.py
index cf7d009c..af02fb66 100644
--- a/qinling/db/api.py
+++ b/qinling/db/api.py
@@ -137,3 +137,11 @@ def create_function_service_mapping(values):
 
 def get_function_service_mapping(function_id):
     return IMPL.get_function_service_mapping(function_id)
+
+
+def get_function_service_mappings(**kwargs):
+    return IMPL.get_function_service_mappings(**kwargs)
+
+
+def delete_function_service_mapping(id):
+    return IMPL.delete_function_service_mapping(id)
diff --git a/qinling/db/sqlalchemy/api.py b/qinling/db/sqlalchemy/api.py
index 87cb6773..580f1e75 100644
--- a/qinling/db/sqlalchemy/api.py
+++ b/qinling/db/sqlalchemy/api.py
@@ -143,7 +143,7 @@ def _get_collection(model, insecure=False, limit=None, marker=None,
         if fields else ()
     )
 
-    query = (db_base.model_query(model, *columns) if insecure
+    query = (db_base.model_query(model, columns) if insecure
              else _secure_query(model, *columns))
     query = db_filters.apply_filters(query, model, **filters)
 
@@ -325,3 +325,17 @@ def get_function_service_mapping(function_id, session=None):
         )
 
     return mapping
+
+
+@db_base.session_aware()
+def get_function_service_mappings(session=None, **kwargs):
+    return _get_collection_sorted_by_time(
+        models.FunctionServiceMapping, **kwargs
+    )
+
+
+@db_base.session_aware()
+def delete_function_service_mapping(id, session=None):
+    mapping = get_function_service_mapping(id)
+
+    session.delete(mapping)
diff --git a/qinling/db/sqlalchemy/filters.py b/qinling/db/sqlalchemy/filters.py
index 84faa920..029c29fd 100644
--- a/qinling/db/sqlalchemy/filters.py
+++ b/qinling/db/sqlalchemy/filters.py
@@ -12,8 +12,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import sqlalchemy as sa
-
 
 def apply_filters(query, model, **filters):
     filter_dict = {}
@@ -45,22 +43,6 @@ def apply_filters(query, model, **filters):
         else:
             filter_dict[key] = value
 
-    # We need to handle tag case seprately. As tag datatype is MutableList.
-    # TODO(hparekh): Need to think how can we get rid of this.
-    tags = filters.pop('tags', None)
-
-    # To match the tag list, a resource must contain at least all of the
-    # tags present in the filter parameter.
-    if tags:
-        tag_attr = getattr(model, 'tags')
-
-        if not isinstance(tags, list):
-            expr = tag_attr.contains(tags)
-        else:
-            expr = sa.and_(*[tag_attr.contains(tag) for tag in tags])
-
-        query = query.filter(expr)
-
     if filter_dict:
         query = query.filter_by(**filter_dict)
 
diff --git a/qinling/db/sqlalchemy/migration/alembic_migrations/versions/001_pike.py b/qinling/db/sqlalchemy/migration/alembic_migrations/versions/001_pike.py
index 8b394cd1..fc7225c9 100644
--- a/qinling/db/sqlalchemy/migration/alembic_migrations/versions/001_pike.py
+++ b/qinling/db/sqlalchemy/migration/alembic_migrations/versions/001_pike.py
@@ -57,6 +57,7 @@ def upgrade():
         sa.Column('timeout', sa.Integer, nullable=True),
         sa.Column('code', st.JsonLongDictType(), nullable=False),
         sa.Column('entry', sa.String(length=80), nullable=False),
+        sa.Column('count', sa.Integer, nullable=False),
         sa.PrimaryKeyConstraint('id'),
         sa.UniqueConstraint('name', 'project_id'),
         info={"check_ifexists": True}
@@ -64,11 +65,12 @@ def upgrade():
 
     op.create_table(
         'function_service_mapping',
+        sa.Column('id', sa.String(length=36), nullable=False),
         sa.Column('created_at', sa.DateTime(), nullable=True),
         sa.Column('updated_at', sa.DateTime(), nullable=True),
         sa.Column('function_id', sa.String(length=36), nullable=False),
         sa.Column('service_url', sa.String(length=255), nullable=False),
-        sa.PrimaryKeyConstraint('function_id'),
+        sa.PrimaryKeyConstraint('id'),
         sa.UniqueConstraint('function_id', 'service_url'),
         sa.ForeignKeyConstraint(
             ['function_id'], [u'function.id'], ondelete='CASCADE'
diff --git a/qinling/db/sqlalchemy/models.py b/qinling/db/sqlalchemy/models.py
index e6010533..5d700d88 100644
--- a/qinling/db/sqlalchemy/models.py
+++ b/qinling/db/sqlalchemy/models.py
@@ -32,6 +32,7 @@ class Function(model_base.QinlingSecureModelBase):
     timeout = sa.Column(sa.Integer)
     code = sa.Column(st.JsonLongDictType(), nullable=False)
     entry = sa.Column(sa.String(80), nullable=False)
+    count = sa.Column(sa.Integer, default=0)
 
 
 class FunctionServiceMapping(model_base.QinlingModelBase):
@@ -41,10 +42,10 @@ class FunctionServiceMapping(model_base.QinlingModelBase):
         sa.UniqueConstraint('function_id', 'service_url'),
     )
 
+    id = model_base.id_column()
     function_id = sa.Column(
         sa.String(36),
         sa.ForeignKey(Function.id, ondelete='CASCADE'),
-        primary_key=True,
     )
     service_url = sa.Column(sa.String(255), nullable=False)
 
diff --git a/qinling/engine/default_engine.py b/qinling/engine/default_engine.py
index cb3d8d3e..2751ce9d 100644
--- a/qinling/engine/default_engine.py
+++ b/qinling/engine/default_engine.py
@@ -127,10 +127,9 @@ class DefaultEngine(object):
                 }
                 db_api.create_function_service_mapping(mapping)
 
-    def delete_function(self, ctx, function_id, function_name):
+    def delete_function(self, ctx, function_id):
         LOG.info('Start to delete function, id=%s', function_id)
 
-        labels = {
-            'function_name': function_name, 'function_id': function_id
-        }
-        self.orchestrator.delete_function(labels)
+        labels = {'function_id': function_id}
+
+        self.orchestrator.delete_function(function_id, labels=labels)
diff --git a/qinling/engine/service.py b/qinling/engine/service.py
index f0d6c98d..b3ece4c5 100644
--- a/qinling/engine/service.py
+++ b/qinling/engine/service.py
@@ -15,12 +15,14 @@
 from oslo_config import cfg
 from oslo_log import log as logging
 import oslo_messaging as messaging
+from oslo_messaging.rpc import dispatcher
 from oslo_service import service
 
 from qinling.db import api as db_api
 from qinling.engine import default_engine as engine
 from qinling.orchestrator import base as orchestra_base
 from qinling import rpc
+from qinling.services import periodics
 
 LOG = logging.getLogger(__name__)
 CONF = cfg.CONF
@@ -35,34 +37,41 @@ class EngineService(service.Service):
     def start(self):
         orchestrator = orchestra_base.load_orchestrator(CONF)
 
+        db_api.setup_db()
+
+        LOG.info('Starting periodic tasks...')
+        periodics.start(orchestrator)
+
         topic = CONF.engine.topic
         server = CONF.engine.host
         transport = messaging.get_transport(CONF)
         target = messaging.Target(topic=topic, server=server, fanout=False)
         endpoints = [engine.DefaultEngine(orchestrator)]
+        access_policy = dispatcher.DefaultRPCAccessPolicy
         self.server = messaging.get_rpc_server(
             transport,
             target,
             endpoints,
             executor='eventlet',
+            access_policy=access_policy,
             serializer=rpc.ContextSerializer(
                 messaging.serializer.JsonPayloadSerializer())
         )
 
-        db_api.setup_db()
-
         LOG.info('Starting engine...')
         self.server.start()
 
         super(EngineService, self).start()
 
     def stop(self, graceful=False):
+        periodics.stop()
+
         if self.server:
             LOG.info('Stopping engine...')
             self.server.stop()
             if graceful:
                 LOG.info(
-                    'Consumer successfully stopped.  Waiting for final '
+                    'Consumer successfully stopped. Waiting for final '
                     'messages to be processed...'
                 )
                 self.server.wait()
diff --git a/qinling/orchestrator/base.py b/qinling/orchestrator/base.py
index 9ff083d0..d5146e59 100644
--- a/qinling/orchestrator/base.py
+++ b/qinling/orchestrator/base.py
@@ -43,7 +43,7 @@ class OrchestratorBase(object):
         raise NotImplementedError
 
     @abc.abstractmethod
-    def delete_function(self, labels):
+    def delete_function(self, function_id, **kwargs):
         raise NotImplementedError
 
 
diff --git a/qinling/orchestrator/kubernetes/manager.py b/qinling/orchestrator/kubernetes/manager.py
index 529323d1..1e58267f 100644
--- a/qinling/orchestrator/kubernetes/manager.py
+++ b/qinling/orchestrator/kubernetes/manager.py
@@ -157,7 +157,7 @@ class KubernetesManager(base.OrchestratorBase):
 
         return pod
 
-    def _prepare_pod(self, pod, deployment_name, function_id, service_labels):
+    def _prepare_pod(self, pod, deployment_name, function_id, labels):
         """Pod preparation.
 
         1. Update pod labels.
@@ -186,10 +186,11 @@ class KubernetesManager(base.OrchestratorBase):
 
         # Create service for the choosen pod.
         service_name = "service-%s" % function_id
+        labels.update({'function_id': function_id})
         service_body = self.service_template.render(
             {
                 "service_name": service_name,
-                "labels": service_labels,
+                "labels": labels,
                 "selector": pod_labels
             }
         )
@@ -322,10 +323,24 @@ class KubernetesManager(base.OrchestratorBase):
 
             return {'result': output}
 
-    def delete_function(self, labels):
+    def delete_function(self, function_id, labels=[]):
         selector = common.convert_dict_to_string(labels)
 
+        ret = self.v1.list_namespaced_service(
+            self.conf.kubernetes.namespace, label_selector=selector
+        )
+        names = [i.metadata.name for i in ret.items]
+        for svc_name in names:
+            self.v1.delete_namespaced_service(
+                svc_name,
+                self.conf.kubernetes.namespace,
+            )
+
+        LOG.info("Services for function %s deleted.", function_id)
+
         self.v1.delete_collection_namespaced_pod(
             self.conf.kubernetes.namespace,
             label_selector=selector
         )
+
+        LOG.info("Pod for function %s deleted.", function_id)
diff --git a/qinling/rpc.py b/qinling/rpc.py
index 9df2a53c..54a72ecf 100644
--- a/qinling/rpc.py
+++ b/qinling/rpc.py
@@ -170,10 +170,9 @@ class EngineClient(object):
             )
 
     @wrap_messaging_exception
-    def delete_function(self, id, name):
+    def delete_function(self, id):
         return self._client.prepare(topic=self.topic, server=None).cast(
             ctx.get_ctx(),
             'delete_function',
-            function_id=id,
-            function_name=name
+            function_id=id
         )
diff --git a/qinling/services/__init__.py b/qinling/services/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/qinling/services/periodics.py b/qinling/services/periodics.py
new file mode 100644
index 00000000..eb713fc3
--- /dev/null
+++ b/qinling/services/periodics.py
@@ -0,0 +1,82 @@
+# Copyright 2017 Catalyst IT Limited
+#
+#    Licensed under the Apache License, Version 2.0 (the "License");
+#    you may not use this file except in compliance with the License.
+#    You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS,
+#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#    See the License for the specific language governing permissions and
+#    limitations under the License.
+
+from datetime import datetime
+from datetime import timedelta
+
+from oslo_config import cfg
+from oslo_log import log as logging
+from oslo_service import threadgroup
+
+from qinling import context
+from qinling.db import api as db_api
+from qinling import rpc
+
+LOG = logging.getLogger(__name__)
+CONF = cfg.CONF
+_THREAD_GROUP = None
+
+
+def handle_function_service_expiration(ctx, engine_client, orchestrator):
+    context.set_ctx(ctx)
+
+    delta = timedelta(seconds=CONF.engine.function_service_expiration)
+    expiry_time = datetime.utcnow() - delta
+
+    results = db_api.get_functions(
+        fields=['id'],
+        sort_keys=['updated_at'],
+        insecure=True,
+        updated_at={'lte': expiry_time}
+    )
+
+    expiry_ids = [ret.id for ret in results]
+
+    if not expiry_ids:
+        return
+
+    mappings = db_api.get_function_service_mappings(
+        function_id={'in': expiry_ids}
+    )
+
+    LOG.info('Found total expiry function mapping numbers: %s', len(mappings))
+
+    with db_api.transaction():
+        for m in mappings:
+            LOG.info('Deleting service mapping for function %s', m.function_id)
+
+            engine_client.delete_function(m.function_id)
+            db_api.delete_function_service_mapping(m.function_id)
+
+
+def start(orchestrator):
+    global _THREAD_GROUP
+    _THREAD_GROUP = threadgroup.ThreadGroup()
+
+    engine_client = rpc.get_engine_client()
+
+    _THREAD_GROUP.add_timer(
+        300,
+        handle_function_service_expiration,
+        ctx=context.Context(),
+        engine_client=engine_client,
+        orchestrator=orchestrator
+    )
+
+
+def stop():
+    global _THREAD_GROUP
+
+    if _THREAD_GROUP:
+        _THREAD_GROUP.stop()