Improve filter_scheduler performance

Add 'columns_to_join' keyword arg to instance_get_all() and have the
scheduler host_manager only join 'instance_type'.  It doesn't use
anything else.

Fixes bug 1017769

Change-Id: Ia2c0956d2453f00e26eb89d9496a32ba15d970aa

5 files changed, 17 insertions, 12 deletions

diff --git a/nova/db/api.py b/nova/db/api.py
index e0d150506..6843412e5 100644
--- a/nova/db/api.py
+++ b/nova/db/api.py
@@ -563,9 +563,9 @@ def instance_get(context, instance_id):
     return IMPL.instance_get(context, instance_id)
 
 
-def instance_get_all(context):
+def instance_get_all(context, columns_to_join=None):
     """Get all instances."""
-    return IMPL.instance_get_all(context)
+    return IMPL.instance_get_all(context, columns_to_join=columns_to_join)
 
 
 def instance_get_all_by_filters(context, filters, sort_key='created_at',
diff --git a/nova/db/sqlalchemy/api.py b/nova/db/sqlalchemy/api.py
index eabd03a22..8d9687120 100644
--- a/nova/db/sqlalchemy/api.py
+++ b/nova/db/sqlalchemy/api.py
@@ -1435,13 +1435,14 @@ def _build_instance_get(context, session=None):
 
 
 @require_admin_context
-def instance_get_all(context):
-    return model_query(context, models.Instance).\
-                   options(joinedload('info_cache')).\
-                   options(joinedload('security_groups')).\
-                   options(joinedload('metadata')).\
-                   options(joinedload('instance_type')).\
-                   all()
+def instance_get_all(context, columns_to_join=None):
+    if columns_to_join is None:
+        columns_to_join = ['info_cache', 'security_groups',
+                           'metadata', 'instance_type']
+    query = model_query(context, models.Instance)
+    for column in columns_to_join:
+        query = query.options(joinedload(column))
+    return query.all()
 
 
 @require_context
diff --git a/nova/scheduler/host_manager.py b/nova/scheduler/host_manager.py
index 2d5f41bae..6de5ebc8f 100644
--- a/nova/scheduler/host_manager.py
+++ b/nova/scheduler/host_manager.py
@@ -333,7 +333,8 @@ class HostManager(object):
             host_state_map[host] = host_state
 
         # "Consume" resources from the host the instance resides on.
-        instances = db.instance_get_all(context)
+        instances = db.instance_get_all(context,
+                columns_to_join=['instance_type'])
         for instance in instances:
             host = instance['host']
             if not host:
diff --git a/nova/tests/scheduler/fakes.py b/nova/tests/scheduler/fakes.py
index 83fbfe8b7..29d4807ac 100644
--- a/nova/tests/scheduler/fakes.py
+++ b/nova/tests/scheduler/fakes.py
@@ -139,4 +139,5 @@ def mox_host_manager_db_calls(mock, context):
     mock.StubOutWithMock(db, 'instance_get_all')
 
     db.compute_node_get_all(mox.IgnoreArg()).AndReturn(COMPUTE_NODES)
-    db.instance_get_all(mox.IgnoreArg()).AndReturn(INSTANCES)
+    db.instance_get_all(mox.IgnoreArg(),
+            columns_to_join=['instance_type']).AndReturn(INSTANCES)
diff --git a/nova/tests/scheduler/test_host_manager.py b/nova/tests/scheduler/test_host_manager.py
index 987bffea1..d28e51c00 100644
--- a/nova/tests/scheduler/test_host_manager.py
+++ b/nova/tests/scheduler/test_host_manager.py
@@ -250,7 +250,9 @@ class HostManagerTestCase(test.TestCase):
         db.compute_node_get_all(context).AndReturn(fakes.COMPUTE_NODES)
         # Invalid service
         host_manager.LOG.warn("No service for compute ID 5")
-        db.instance_get_all(context).AndReturn(fakes.INSTANCES)
+        db.instance_get_all(context,
+                columns_to_join=['instance_type']).AndReturn(
+                        fakes.INSTANCES)
 
         self.mox.ReplayAll()
         host_states = self.host_manager.get_all_host_states(context, topic)