vGPU multiple instance creation test is racey

[Sylvain Bauza]

Zuul can fail sometimes on :
2020-05-05 09:07:46.656481 | ubuntu-bionic | ==============================
2020-05-05 09:07:46.656502 | ubuntu-bionic | Failed 1 tests - output below:
2020-05-05 09:07:46.656518 | ubuntu-bionic | ==============================
2020-05-05 09:07:46.656533 | ubuntu-bionic |
2020-05-05 09:07:46.656548 | ubuntu-bionic | nova.tests.functional.libvirt.test_vgpu.VGPUTests.test_multiple_instance_create
2020-05-05 09:07:46.656563 | ubuntu-bionic | -------------------------------------------------------------------------------
2020-05-05 09:07:46.656577 | ubuntu-bionic |
2020-05-05 09:07:46.656594 | ubuntu-bionic | Captured traceback:
2020-05-05 09:07:46.656609 | ubuntu-bionic | ~~~~~~~~~~~~~~~~~~~
2020-05-05 09:07:46.656625 | ubuntu-bionic | Traceback (most recent call last):
2020-05-05 09:07:46.656651 | ubuntu-bionic |
2020-05-05 09:07:46.656669 | ubuntu-bionic | File "/home/zuul/src/opendev.org/openstack/nova/nova/tests/functional/libvirt/test_vgpu.py", line 248, in test_multiple_instance_create
2020-05-05 09:07:46.656686 | ubuntu-bionic | self.assert_vgpu_usage_for_compute(self.compute1, expected=2)
2020-05-05 09:07:46.656701 | ubuntu-bionic |
2020-05-05 09:07:46.656716 | ubuntu-bionic | File "/home/zuul/src/opendev.org/openstack/nova/nova/tests/functional/libvirt/test_vgpu.py", line 178, in assert_vgpu_usage_for_compute
2020-05-05 09:07:46.656732 | ubuntu-bionic | self.assertEqual(expected, len(mdevs))
2020-05-05 09:07:46.656784 | ubuntu-bionic |
2020-05-05 09:07:46.656803 | ubuntu-bionic | File "/home/zuul/src/opendev.org/openstack/nova/.tox/functional-py36/lib/python3.6/site-packages/testtools/testcase.py", line 415, in assertEqual
2020-05-05 09:07:46.656818 | ubuntu-bionic | self.assertThat(observed, matcher, message)
2020-05-05 09:07:46.656834 | ubuntu-bionic |
2020-05-05 09:07:46.656848 | ubuntu-bionic | File "/home/zuul/src/opendev.org/openstack/nova/.tox/functional-py36/lib/python3.6/site-packages/testtools/testcase.py", line 502, in assertThat
2020-05-05 09:07:46.656863 | ubuntu-bionic | raise mismatch_error
2020-05-05 09:07:46.656878 | ubuntu-bionic |
2020-05-05 09:07:46.656892 | ubuntu-bionic | testtools.matchers._impl.MismatchError: 2 != 1
2020-05-05 09:07:46.656907 | ubuntu-bionic |

Logstash query :
http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22testtools.matchers._impl.MismatchError%3A%202%20!%3D%201%5C%22%20AND%20build_name%3A%5C%22nova-tox-functional-py36%5C%22

8 occurrences over 7 days.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/726087

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/726087
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=dc5dc4de2f8b3de60c36ef772c00be1fc278c6f0
Submitter: Zuul
Branch: master

commit dc5dc4de2f8b3de60c36ef772c00be1fc278c6f0
Author: Sylvain Bauza <email address hidden>
Date: Thu May 7 12:32:14 2020 +0200

    Wait for all servers to be active when testing vGPUs

    We were just verifying the state of the first server before introspecting
    the number of created devices. If the second server isn't ACTIVE yet,
    then the mdevs wouldn't be found and the functest would return an exception.

    Change-Id: I02a9f26dea6378281f3968a2c5cf0f652f9e342b
    Closes-Bug: #1877281