diff --git a/nova/cmd/scheduler.py b/nova/cmd/scheduler.py index 51d5aee4ac..dafec005b4 100644 --- a/nova/cmd/scheduler.py +++ b/nova/cmd/scheduler.py @@ -18,6 +18,7 @@ import sys +from oslo_concurrency import processutils from oslo_log import log as logging from oslo_reports import guru_meditation_report as gmr from oslo_reports import opts as gmr_opts @@ -45,5 +46,11 @@ def main(): server = service.Service.create(binary='nova-scheduler', topic=scheduler_rpcapi.RPC_TOPIC) - service.serve(server) + # Determine the number of workers; if not specified in config, default + # to ncpu for the FilterScheduler and 1 for everything else. + workers = CONF.scheduler.workers + if not workers: + workers = (processutils.get_worker_count() + if CONF.scheduler.driver == 'filter_scheduler' else 1) + service.serve(server, workers=workers) service.wait() diff --git a/nova/conf/scheduler.py b/nova/conf/scheduler.py index 404b9af60e..55927a75cd 100644 --- a/nova/conf/scheduler.py +++ b/nova/conf/scheduler.py @@ -63,6 +63,10 @@ Possible values: * You may also set this to the entry point name of a custom scheduler driver, but you will be responsible for creating and maintaining it in your setup.cfg file. + +Related options: + +* workers """), cfg.IntOpt("periodic_task_interval", default=60, @@ -139,6 +143,13 @@ etc. of the scheduler. This option is only used by the FilterScheduler; if you use a different scheduler, this option has no effect. +"""), + cfg.IntOpt("workers", + min=0, + help=""" +Number of workers for the nova-scheduler service. The default will be the +number of CPUs available if using the "filter_scheduler" scheduler driver, +otherwise the default will be 1. """), ] diff --git a/nova/tests/unit/cmd/test_scheduler.py b/nova/tests/unit/cmd/test_scheduler.py new file mode 100644 index 0000000000..2d5029cb82 --- /dev/null +++ b/nova/tests/unit/cmd/test_scheduler.py @@ -0,0 +1,61 @@ +# Licensed under the Apache License, Version 2.0 (the "License"); you may +# not use this file except in compliance with the License. You may obtain +# a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT +# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the +# License for the specific language governing permissions and limitations +# under the License. + +import mock + +from nova.cmd import scheduler +from nova import config +from nova import test + + +# required because otherwise oslo early parse_args dies +@mock.patch.object(config, 'parse_args', new=lambda *args, **kwargs: None) +class TestScheduler(test.NoDBTestCase): + + @mock.patch('nova.service.Service.create') + @mock.patch('nova.service.serve') + @mock.patch('nova.service.wait') + @mock.patch('oslo_concurrency.processutils.get_worker_count', + return_value=2) + def test_workers_defaults(self, get_worker_count, mock_wait, mock_serve, + service_create): + scheduler.main() + get_worker_count.assert_called_once_with() + mock_serve.assert_called_once_with( + service_create.return_value, workers=2) + mock_wait.assert_called_once_with() + + @mock.patch('nova.service.Service.create') + @mock.patch('nova.service.serve') + @mock.patch('nova.service.wait') + @mock.patch('oslo_concurrency.processutils.get_worker_count') + def test_workers_override(self, get_worker_count, mock_wait, mock_serve, + service_create): + self.flags(workers=4, group='scheduler') + scheduler.main() + get_worker_count.assert_not_called() + mock_serve.assert_called_once_with( + service_create.return_value, workers=4) + mock_wait.assert_called_once_with() + + @mock.patch('nova.service.Service.create') + @mock.patch('nova.service.serve') + @mock.patch('nova.service.wait') + @mock.patch('oslo_concurrency.processutils.get_worker_count') + def test_workers_caching_scheduler(self, get_worker_count, mock_wait, + mock_serve, service_create): + self.flags(driver='caching_scheduler', group='scheduler') + scheduler.main() + get_worker_count.assert_not_called() + mock_serve.assert_called_once_with( + service_create.return_value, workers=1) + mock_wait.assert_called_once_with() diff --git a/releasenotes/notes/multiple-scheduler-workers-3e5ac0d86f436338.yaml b/releasenotes/notes/multiple-scheduler-workers-3e5ac0d86f436338.yaml new file mode 100644 index 0000000000..58a80e22d2 --- /dev/null +++ b/releasenotes/notes/multiple-scheduler-workers-3e5ac0d86f436338.yaml @@ -0,0 +1,26 @@ +--- +features: + - | + It is now possible to configure multiple *nova-scheduler* workers via the + ``[scheduler]workers`` configuration option. By default, the option runs + ``ncpu`` workers if using the ``filter_scheduler`` scheduler driver, + otherwise the default is 1. + + Since `blueprint placement-claims`_ in Pike, the FilterScheduler + uses the Placement service to create resource allocations (claims) + against a resource provider (i.e. compute node) chosen by the scheduler. + That reduces the risk of scheduling collisions when running multiple + schedulers. + + Since other scheduler drivers, like the CachingScheduler, do not + use Placement, it is recommended to set workers=1 (default) for those + other scheduler drivers. + + .. _blueprint placement-claims: https://specs.openstack.org/openstack/nova-specs/specs/pike/implemented/placement-claims.html +upgrade: + - | + The new ``[scheduler]workers`` configuration option defaults to ``ncpu`` + workers if using the ``filter_scheduler`` scheduler driver. If you are + running *nova-scheduler* on the same host as other services, you may want + to change this default value, or to otherwise account for running other + instances of the *nova-scheduler* service. \ No newline at end of file