openstack/nova
Code Issues Proposed changes

refresh instances_path when shared storage used

Browse Source 
When doing Live migration with shared storage, it happens erratically,
that the check for the shared storage test_file fails. Because the shared
volume is under heavy IO (many instances on many compute nodes) the client
does not immediately sees the new content of the folder. This delay
could take up to 30s.
This can be fixed if the client is forced to refresh the directories
content, which can be achieved by 'touch' on the directory. Doing so,
the test_file is visibile instantly, within ms.
The patch adds a 'touch' on instances_path in check_shared_storage_test_file,
before checking the existence of the file.

Conflicts:
    nova/tests/unit/virt/libvirt/test_driver.py

NOTE(lyarwood): Conflict caused by the signature of
_check_shared_storage_test_file changing as part of I6cca257

Change-Id: I16be39142278517f43e6eca3441a56cbc9561113
Closes-Bug: #1617299
(cherry picked from commit 1af73d1fb3)
This commit is contained in:
Tom Patzig 2016-09-07 11:16:49 +02:00 committed by Lee Yarwood
parent 63f3d99819
commit eeb23c7891
2 changed files with 28 additions and 0 deletions
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20
nova/tests/unit/virt/libvirt/test_driver.py
View File

@ -6428,6 +6428,26 @@ class LibvirtConnTestCase(test.NoDBTestCase):
drvr.check_can_live_migrate_destination_cleanup(self.context, drvr.check_can_live_migrate_destination_cleanup(self.context,
dest_check_data) dest_check_data)
@mock.patch('os.path.exists', return_value=True)
@mock.patch('os.utime')
def test_check_shared_storage_test_file_exists(self, mock_utime,
mock_path_exists):
tmpfile_path = os.path.join(CONF.instances_path, 'tmp123')
drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
self.assertTrue(drvr._check_shared_storage_test_file('tmp123'))
mock_utime.assert_called_once_with(CONF.instances_path, None)
mock_path_exists.assert_called_once_with(tmpfile_path)
@mock.patch('os.path.exists', return_value=False)
@mock.patch('os.utime')
def test_check_shared_storage_test_file_does_not_exist(self, mock_utime,
mock_path_exists):
tmpfile_path = os.path.join(CONF.instances_path, 'tmp123')
drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
self.assertFalse(drvr._check_shared_storage_test_file('tmp123'))
mock_utime.assert_called_once_with(CONF.instances_path, None)
mock_path_exists.assert_called_once_with(tmpfile_path)
def _mock_can_live_migrate_source(self, block_migration=False, def _mock_can_live_migrate_source(self, block_migration=False,
is_shared_block_storage=False, is_shared_block_storage=False,
is_shared_instance_path=False, is_shared_instance_path=False,

8
nova/virt/libvirt/driver.py
View File

@ -5749,6 +5749,14 @@ class LibvirtDriver(driver.ComputeDriver):
Cannot confirm tmpfile return False. Cannot confirm tmpfile return False.
""" """
# NOTE(tpatzig): if instances_path is a shared volume that is
# under heavy IO (many instances on many compute nodes),
# then checking the existence of the testfile fails,
# just because it takes longer until the client refreshes and new
# content gets visible.
# os.utime (like touch) on the directory forces the client to refresh.
os.utime(CONF.instances_path, None)
tmp_file = os.path.join(CONF.instances_path, filename) tmp_file = os.path.join(CONF.instances_path, filename)
if not os.path.exists(tmp_file): if not os.path.exists(tmp_file):
return False return False