Description of problem: Large heat stack creates get progressively longer, It seems the DB needs to be cleaned. However heat purge_deleted fails to work.

stack create seems to get longer as the db fills up. heat-manage purge_deleted should purge the db but the command fails :
[root@slnec2ctl2 log]# heat-manage --debug -v purge_deleted -g days 1
2016-03-08 10:16:08.836 9254 ERROR oslo_db.sqlalchemy.exc_filters [-] DB
exception wrapped.
2016-03-08 10:16:08.836 9254 TRACE oslo_db.sqlalchemy.exc_filters Traceback
(most recent call last):
2016-03-08 10:16:08.836 9254 TRACE oslo_db.sqlalchemy.exc_filters   File
"/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 316,
in connection
2016-03-08 10:16:08.836 9254 TRACE oslo_db.sqlalchemy.exc_filters
return self._revalidate_connection()
2016-03-08 10:16:08.836 9254 TRACE oslo_db.sqlalchemy.exc_filters   File
"/usr/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 396,
in _revalidate_connection
2016-03-08 10:16:08.836 9254 TRACE oslo_db.sqlalchemy.exc_filters     raise
exc.ResourceClosedError("This Connection is closed")
2016-03-08 10:16:08.836 9254 TRACE oslo_db.sqlalchemy.exc_filters
ResourceClosedError: This Connection is closed
2016-03-08 10:16:08.836 9254 TRACE oslo_db.sqlalchemy.exc_filters
ERROR: This Connection is closed


Version-Release number of selected component (if applicable):
openstack-heat-api-2015.1.2-6.el7ost.noarch

How reproducible:


Steps to Reproduce:
1.create several large heat stacks
2.attempt to purge DB
3.

Actual results:
fails with errros above

Expected results:
DB should be cleaned

Additional info: