I am autoscaling a stack on heat. When i run the stress command in stack to put some load on it for increasing the memory usage and autoscale this error appear in heat engine logs.

2014-05-19 17:14:45.216 INFO heat.engine.watchrule [-] WATCH: stack:90d53942-7cd1-4bc2-b003-8067cb1fee2d, watch_name:demg-MEMAlarmLow, new_state:ALARM

2014-05-19 17:14:45.265 INFO heat.engine.watchrule [-] WATCH: stack:90d53942-7cd1-4bc2-b003-8067cb1fee2d, watch_name:demg-MEMAlarmHigh, new_state:NORMAL

2014-05-19 17:14:45.266 INFO heat.engine.watchrule [-] no action for new state NORMAL 2014-05-19 17:14:45.268 ERROR heat.openstack.common.db.sqlalchemy.session [-] DB exception wrapped. 2014-05-19 17:14:45.268 TRACE heat.openstack.common.db.sqlalchemy.session Traceback (most recent call last):

2014-05-19 17:14:45.268 TRACE heat.openstack.common.db.sqlalchemy.session File "/opt/stack/heat/heat/openstack/common/db/sqlalchemy/session.py", line 439, in _wrap 2014-05-19 17:14:45.268 TRACE heat.openstack.common.db.sqlalchemy.session return f(self, args, *kwargs) 2014-05-19 17:14:45.268 TRACE heat.openstack.common.db.sqlalchemy.session File "/opt/stack/heat/heat/openstack/common/db/sqlalchemy/session.py", line 705, in flush 2014-05-19 17:14:45.268 TRACE heat.openstack.common.db.sqlalchemy.session return super(Session, self).flush(args, *kwargs)

2014-05-19 17:14:45.268 TRACE heat.openstack.common.db.sqlalchemy.session File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 1812, in flush 2014-05-19 17:14:45.268 TRACE heat.openstack.common.db.sqlalchemy.session raise sa_exc.InvalidRequestError("Session is already flushing") 2014-05-19 17:14:45.268 TRACE heat.openstack.common.db.sqlalchemy.session InvalidRequestError: Session is already flushing 2014-05-19 17:14:45.268 TRACE heat.openstack.common.db.sqlalchemy.session 2014-05-19 17:14:45.274 ERROR heat.engine.resource [-] signal ScalingPolicy "WebServerScaleDownPolicy" [b0eb686fc78c49cb8a5598b375dcd927] Stack "demg" [90d53942-7cd1-4bc2-b003-8067cb1fee2d] : Session is already flushing

2014-05-19 17:14:45.274 TRACE heat.engine.resource Traceback (most recent call last): 2014-05-19 17:14:45.274 TRACE heat.engine.resource File "/opt/stack/heat/heat/engine/resource.py", line 882, in signal 2014-05-19 17:14:45.274 TRACE heat.engine.resource
self._add_event('signal', self.status, get_string_details()) 2014-05-19 17:14:45.274 TRACE heat.engine.resource File "/opt/stack/heat/heat/engine/resource.py", line 750, in _add_event 2014-05-19 17:14:45.274 TRACE heat.engine.resource ev.store() 2014-05-19 17:14:45.274 TRACE heat.engine.resource File "/opt/stack/heat/heat/engine/event.py", line 93, in store

2014-05-19 17:14:45.274 TRACE heat.engine.resource new_ev = db_api.event_create(self.context, ev) 2014-05-19 17:14:45.274 TRACE heat.engine.resource File "/opt/stack/heat/heat/db/api.py", line 199, in event_create 2014-05-19 17:14:45.274 TRACE heat.engine.resource return IMPL.event_create(context, values) 2014-05-19 17:14:45.274 TRACE heat.engine.resource File "/opt/stack/heat/heat/db/sqlalchemy/api.py", line 579, in event_create 2014-05-19 17:14:45.274 TRACE heat.engine.resource
event_ref.save(_session(context)) 2014-05-19 17:14:45.274 TRACE heat.engine.resource File "/opt/stack/heat/heat ...