Merge "[ironic] Minimize window for a resource provider to be lost" into stable/victoria

3 files changed, 40 insertions, 1 deletions

diff --git a/nova/tests/unit/virt/ironic/test_driver.py b/nova/tests/unit/virt/ironic/test_driver.py
index 9b8a6a0472..801846c4dd 100644
--- a/nova/tests/unit/virt/ironic/test_driver.py
+++ b/nova/tests/unit/virt/ironic/test_driver.py
@@ -3441,6 +3441,9 @@ class NodeCacheTestCase(test.NoDBTestCase):
         mock_instances.return_value = instances
         mock_nodes.return_value = nodes
         mock_hosts.side_effect = hosts
+        parent_mock = mock.MagicMock()
+        parent_mock.attach_mock(mock_nodes, 'get_node_list')
+        parent_mock.attach_mock(mock_instances, 'get_uuids_by_host')
         if not can_send_146:
             mock_can_send.side_effect = (
                 exception.IronicAPIVersionNotAvailable(version='1.46'))
@@ -3453,6 +3456,15 @@ class NodeCacheTestCase(test.NoDBTestCase):
 
         self.driver._refresh_cache()
 
+        # assert if get_node_list() is called before get_uuids_by_host()
+        parent_mock.assert_has_calls(
+            [
+                mock.call.get_node_list(fields=ironic_driver._NODE_FIELDS,
+                                        **kwargs),
+                mock.call.get_uuids_by_host(mock.ANY, self.host)
+            ]
+        )
+
         mock_hash_ring.assert_called_once_with(mock.ANY)
         mock_instances.assert_called_once_with(mock.ANY, self.host)
         mock_nodes.assert_called_once_with(fields=ironic_driver._NODE_FIELDS,
diff --git a/nova/virt/ironic/driver.py b/nova/virt/ironic/driver.py
index aa00ef6839..3bd4d18ecc 100644
--- a/nova/virt/ironic/driver.py
+++ b/nova/virt/ironic/driver.py
@@ -788,10 +788,15 @@ class IronicDriver(virt_driver.ComputeDriver):
     def _refresh_cache(self):
         ctxt = nova_context.get_admin_context()
         self._refresh_hash_ring(ctxt)
-        instances = objects.InstanceList.get_uuids_by_host(ctxt, CONF.host)
         node_cache = {}
 
         def _get_node_list(**kwargs):
+            # NOTE(TheJulia): This call can take a substantial amount
+            # of time as it may be attempting to retrieve thousands of
+            # baremetal nodes. Depending on the version of Ironic,
+            # this can be as long as 2-10 seconds per every thousand
+            # nodes, and this call may retrieve all nodes in a deployment,
+            # depending on if any filter paramters are applied.
             return self._get_node_list(fields=_NODE_FIELDS, **kwargs)
 
         # NOTE(jroll) if partition_key is set, we need to limit nodes that
@@ -815,6 +820,15 @@ class IronicDriver(virt_driver.ComputeDriver):
         else:
             nodes = _get_node_list()
 
+        # NOTE(saga): As _get_node_list() will take a long
+        # time to return in large clusters we need to call it before
+        # get_uuids_by_host() method. Otherwise the instances list we get from
+        # get_uuids_by_host() method will become stale.
+        # A stale instances list can cause a node that is managed by this
+        # compute host to be excluded in error and cause the compute node
+        # to be orphaned and associated resource provider to be deleted.
+        instances = objects.InstanceList.get_uuids_by_host(ctxt, CONF.host)
+
         for node in nodes:
             # NOTE(jroll): we always manage the nodes for instances we manage
             if node.instance_uuid in instances:
diff --git a/releasenotes/notes/minimize-bug-1841481-race-window-f76912d4985770ad.yaml b/releasenotes/notes/minimize-bug-1841481-race-window-f76912d4985770ad.yaml
new file mode 100644
index 0000000000..a49d64c6ac
--- /dev/null
+++ b/releasenotes/notes/minimize-bug-1841481-race-window-f76912d4985770ad.yaml
@@ -0,0 +1,13 @@
+---
+fixes:
+  - |
+    Minimizes a race condition window when using the ``ironic`` virt driver
+    where the data generated for the Resource Tracker may attempt to compare
+    potentially stale instance information with the latest known baremetal
+    node information. While this doesn't completely prevent nor resolve the
+    underlying race condition identified in
+    `bug 1841481 <https://bugs.launchpad.net/nova/+bug/1841481>`_,
+    this change allows Nova to have the latest state information, as opposed
+    to state information which may be out of date due to the time which it may
+    take to retrieve the status from Ironic. This issue was most observable
+    on baremetal clusters with several thousand physical nodes.