Revert "Log CellTimeout traceback in scatter_gather_cells"

This reverts commit 0436a95f37.

This was meant to get us more debug details when hitting the
failure but the results are not helpful [1] so revert this
and the fix for the resulting regression [2].

[1] http://paste.openstack.org/show/782116/
[2] I7f9edc9a4b4930f4dce98df271888fa8082a1701

Change-Id: Iab8029f081a654278ea7dbbec79a766aea6764ae
Related-Bug: #1844929

nova/context.py

@@ -445,14 +445,15 @@ def scatter_gather_cells(context, cell_mappings, timeout, fn, *args, **kwargs):
         except exception.CellTimeout:
             # NOTE(melwitt): We'll fill in did_not_respond_sentinels at the
             # same time we kill/wait for the green threads.
-            LOG.warning('Timed out waiting for response from cell',
+            pass
-                        exc_info=True)
 
     # Kill the green threads still pending and wait on those we know are done.
     for cell_uuid, greenthread in greenthreads:
         if cell_uuid not in results:
             greenthread.kill()
             results[cell_uuid] = did_not_respond_sentinel
+            LOG.warning('Timed out waiting for response from cell %s',
+                        cell_uuid)
         else:
             greenthread.wait()
 

nova/tests/unit/test_context.py

@@ -385,45 +385,13 @@ class ContextTestCase(test.NoDBTestCase):
                                        exception.CellTimeout()]
 
         results = context.scatter_gather_cells(
-            ctxt, mappings, 30, objects.InstanceList.get_by_filters, {})
+            ctxt, mappings, 30, objects.InstanceList.get_by_filters)
         self.assertEqual(2, len(results))
         self.assertIn(mock.sentinel.instances, results.values())
         self.assertIn(context.did_not_respond_sentinel, results.values())
         mock_timeout.assert_called_once_with(30, exception.CellTimeout)
         self.assertTrue(mock_log_warning.called)
 
-    @mock.patch('nova.context.LOG.warning')
-    @mock.patch('eventlet.timeout.Timeout')
-    @mock.patch('eventlet.queue.LightQueue.get')
-    @mock.patch('nova.objects.InstanceList.get_by_filters')
-    def test_scatter_gather_cells_all_timeout(self, mock_get_inst,
-                                              mock_get_result, mock_timeout,
-                                              mock_log_warning):
-        """This is a regression test for bug 1847131.
-        test_scatter_gather_cells_timeout did not catch the issue because it
-        yields a result which sets the cell_uuid variable in scope before the
-        CellTimeout is processed and logged. In this test we only raise the
-        CellTimeout so cell_uuid will not be in scope for the log message.
-        """
-        # This is needed because we're mocking get_by_filters.
-        self.useFixture(nova_fixtures.SpawnIsSynchronousFixture())
-        ctxt = context.get_context()
-        mapping0 = objects.CellMapping(database_connection='fake://db0',
-                                       transport_url='none:///',
-                                       uuid=objects.CellMapping.CELL0_UUID)
-        mappings = objects.CellMappingList(objects=[mapping0])
-
-        # Simulate cell0 not responding.
-        mock_get_result.side_effect = exception.CellTimeout()
-
-        results = context.scatter_gather_cells(
-            ctxt, mappings, 30, objects.InstanceList.get_by_filters, {})
-        self.assertEqual(1, len(results))
-        self.assertIn(context.did_not_respond_sentinel, results.values())
-        mock_timeout.assert_called_once_with(30, exception.CellTimeout)
-        mock_log_warning.assert_called_once_with(
-            'Timed out waiting for response from cell', exc_info=True)
-
     @mock.patch('nova.context.LOG.exception')
     @mock.patch('nova.objects.InstanceList.get_by_filters')
     def test_scatter_gather_cells_exception(self, mock_get_inst,