Comment 0 for bug 1730556

Description
===========
all periodic tasks of nova-compute don't work
report_state works.

Steps to reproduce
==================
after some error of our virtulization product happened.
At that time, get_available_nodes of the driver can not fulfil and throw a exception that does nto inherit from Excetipn

Expected result
===============
all periodic task should keep going

Actual result
=============
all periodic tasks stop

Analysis
=============
I found that the coroutine has disappear and run_periodic_tasks in periodic_task.py does not catch BaseException

Solution
=============
run_periodic_tasks should catch all exception.
This is a major problem. All periodic_task died even those tasks which work well and don't throw exception.
Because they belong to a same coroutine.
We should keep nova-compute robust.

Environment
===========
1. Exact version of OpenStack you are running. See the following
  list for all releases: http://docs.openstack.org/releases/
   openstack-nova-common-16.0.1-1.el7.noarch
   python2-novaclient-9.1.0-1.noarch
   python-nova-16.0.1-1.el7.noarch
   openstack-nova-compute-16.0.1-1.noarch

2. Which hypervisor did you use?
   Our own virtulization product

2. Which storage type did you use?
   None

3. Which networking type did you use?
   Neutron with our sdn