Got db error when running tempest tests

[Ethan Lynn]

When I run tempest tests, I got following exceptions occasionally.

2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher File "/opt/stack/senlin/senlin/engine/service.py", line 61, in wrapped
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher return func(self, ctx, *args, **kwargs)
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher File "/opt/stack/senlin/senlin/engine/service.py", line 900, in cluster_delete
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher dispatcher.start_action(action_id=action_id)
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher File "/opt/stack/senlin/senlin/engine/dispatcher.py", line 112, in start_action
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher return notify(START_ACTION, engine_id, **kwargs)
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher File "/opt/stack/senlin/senlin/engine/dispatcher.py", line 105, in notify
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher call_context.call(oslo_context.get_current(), method, **kwargs)
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/client.py", line 158, in call
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher retry=self.retry)
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/site-packages/oslo_messaging/transport.py", line 90, in _send
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher timeout=timeout, retry=retry)
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/site-packages/oslo_messaging/_drivers/amqpdriver.py", line 470, in send
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher retry=retry)
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/site-packages/oslo_messaging/_drivers/amqpdriver.py", line 461, in _send
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher raise result
2016-03-30 22:54:25.104 TRACE oslo_messaging.rpc.dispatcher RemoteError: Remote error: InvalidRequestError A transaction is already begun. Use subtransactions=True to allow subtransactions.

Reproduce:
checkout https://review.openstack.org/#/c/295647/
python setup.py install
run tempest tests following README

[Ethan Lynn (ethanlynn)]

I only run one senlin-engine without workers, and set backend to openstack_test.

[Ethan Lynn (ethanlynn)]

Paste the log here:
http://paste.openstack.org/show/492575/

[Ethan Lynn (ethanlynn)]

https://review.openstack.org/#/c/300089/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/300089
Committed: https://git.openstack.org/cgit/openstack/senlin/commit/?id=956b7e80776fc69be900dc81d7c6c6fe8a459c59
Submitter: Jenkins
Branch: master

commit 956b7e80776fc69be900dc81d7c6c6fe8a459c59
Author: Ethan Lynn <email address hidden>
Date: Thu Mar 31 23:36:50 2016 +0800

    Use the new enginefacade from oslo.db

    Use the new enginefacade from oslo.db, this patch
    follow the implementation of keystone.

    Closes-Bug: #1563920
    Change-Id: I636df3a3bd0fd3eef6b8f48cf6bc244392ea6843

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/mitaka
Review: https://review.openstack.org/308797

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/308797
Committed: https://git.openstack.org/cgit/openstack/senlin/commit/?id=48e87c3d72568440175bba15fb0afac28dea5f35
Submitter: Jenkins
Branch: stable/mitaka

commit 48e87c3d72568440175bba15fb0afac28dea5f35
Author: Ethan Lynn <email address hidden>
Date: Thu Mar 31 23:36:50 2016 +0800

    Use the new enginefacade from oslo.db

    Use the new enginefacade from oslo.db, this patch
    follow the implementation of keystone.

    Closes-Bug: #1563920
    Change-Id: I636df3a3bd0fd3eef6b8f48cf6bc244392ea6843
    (cherry picked from commit 956b7e80776fc69be900dc81d7c6c6fe8a459c59)

[Doug Hellmann (doug-hellmann)]

This issue was fixed in the openstack/senlin 2.0.0.0b1 development milestone.