openstack/nova
Code Issues Proposed changes

scheduler: Merge driver into manager

Browse Source 
There's only one driver now, which means there isn't really a driver at
all. Move the code into the manager altogether and avoid a useless layer
of abstraction.

Change-Id: I609df5b707e05ea70c8a738701423ca751682575
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>
This commit is contained in:
Stephen Finucane 2021-06-29 12:31:22 +01:00
parent 289438b4c2
commit 6652999494
9 changed files with 1670 additions and 1747 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
doc/source/contributor/testing/eventlet-profiling.rst
View File

@ -100,20 +100,20 @@ profiling and benchmarking scenarios so not all changes are relevant here):
[notifications]
notification_format = unversioned
Change the code in ``nova/scheduler/driver.py`` as follows to start the
profiler at the start of ``select_destinations`` call and to dump the
Change the code in ``nova/scheduler/manager.py`` as follows to start the
profiler at the start of the ``_select_destinations`` call and to dump the
statistics at the end. For example:
.. code-block:: diff
diff --git nova/scheduler/driver.py nova/scheduler/driver.py
index 555236e8a1..efa84b5a47 100644
--- nova/scheduler/driver.py
+++ nova/scheduler/driver.py
@@ -95,6 +95,10 @@ class SchedulerDriver:
determined by the configuration option
`CONF.scheduler.max_attempts`.
"""
diff --git nova/scheduler/manager.py nova/scheduler/manager.py
index 9cee6b3bfc..4859b21fb1 100644
--- nova/scheduler/manager.py
+++ nova/scheduler/manager.py
@@ -237,6 +237,10 @@ class SchedulerManager(manager.Manager):
alloc_reqs_by_rp_uuid, provider_summaries,
allocation_request_version=None, return_alternates=False,
):
+ from eventlet.green import profile
+ pr = profile.Profile()
+ pr.start()
@ -121,15 +121,14 @@ statistics at the end. For example:
self.notifier.info(
context, 'scheduler.select_destinations.start',
{'request_spec': spec_obj.to_legacy_request_spec_dict()})
@@ -114,6 +118,10 @@ class SchedulerDriver:
context=context, request_spec=spec_obj,
@@ -260,6 +264,9 @@ class SchedulerManager(manager.Manager):
action=fields_obj.NotificationAction.SELECT_DESTINATIONS,
phase=fields_obj.NotificationPhase.END)
+
+ pr.stop()
+ pr.dump_stats('/tmp/select_destinations/%s.prof' % ':'.join(instance_uuids))
+
return host_selections
return selections
def _schedule(

505
nova/scheduler/driver.py
View File

@ -1,505 +0,0 @@
# Copyright (c) 2010 OpenStack Foundation
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
# 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.
"""
Driver for the nova-scheduler service.
You can customize this scheduler by specifying your own host filters and
weighers.
"""
import random
from oslo_log import log as logging
from nova.compute import utils as compute_utils
import nova.conf
from nova import exception
from nova.i18n import _
from nova import objects
from nova.objects import fields as fields_obj
from nova import rpc
from nova.scheduler.client import report
from nova.scheduler import host_manager
from nova.scheduler import utils
from nova import servicegroup
CONF = nova.conf.CONF
LOG = logging.getLogger(__name__)
class SchedulerDriver:
"""The scheduler driver.
Filters and weighs compute hosts to determine the best host to schedule an
instance to.
"""
def __init__(self):
self.host_manager = host_manager.HostManager()
self.servicegroup_api = servicegroup.API()
self.notifier = rpc.get_notifier('scheduler')
self.placement_client = report.SchedulerReportClient()
def select_destinations(
self, context, spec_obj, instance_uuids,
alloc_reqs_by_rp_uuid, provider_summaries,
allocation_request_version=None, return_alternates=False,
):
"""Returns a list of lists of Selection objects that have been chosen
by the scheduler driver, one for each requested instance.
:param context: The RequestContext object
:param spec_obj: The RequestSpec object
:param instance_uuids: List of UUIDs, one for each value of the spec
object's num_instances attribute
:param alloc_reqs_by_rp_uuid: Optional dict, keyed by resource provider
UUID, of the allocation_requests that may be used to claim
resources against matched hosts. If None, indicates either the
placement API wasn't reachable or that there were no
allocation_requests returned by the placement API. If the latter,
the provider_summaries will be an empty dict, not None.
:param provider_summaries: Optional dict, keyed by resource provider
UUID, of information that will be used by the filters/weighers in
selecting matching hosts for a request. If None, indicates that the
scheduler driver should grab all compute node information locally
and that the Placement API is not used. If an empty dict, indicates
the Placement API returned no potential matches for the requested
resources.
:param allocation_request_version: The microversion used to request the
allocations.
:param return_alternates: When True, zero or more alternate hosts are
returned with each selected host. The number of alternates is
determined by the configuration option
`CONF.scheduler.max_attempts`.
"""
self.notifier.info(
context, 'scheduler.select_destinations.start',
{'request_spec': spec_obj.to_legacy_request_spec_dict()})
compute_utils.notify_about_scheduler_action(
context=context, request_spec=spec_obj,
action=fields_obj.NotificationAction.SELECT_DESTINATIONS,
phase=fields_obj.NotificationPhase.START)
host_selections = self._schedule(
context, spec_obj, instance_uuids,
alloc_reqs_by_rp_uuid, provider_summaries,
allocation_request_version, return_alternates)
self.notifier.info(
context, 'scheduler.select_destinations.end',
{'request_spec': spec_obj.to_legacy_request_spec_dict()})
compute_utils.notify_about_scheduler_action(
context=context, request_spec=spec_obj,
action=fields_obj.NotificationAction.SELECT_DESTINATIONS,
phase=fields_obj.NotificationPhase.END)
return host_selections
def _schedule(
self, context, spec_obj, instance_uuids, alloc_reqs_by_rp_uuid,
provider_summaries, allocation_request_version=None,
return_alternates=False
):
"""Returns a list of lists of Selection objects.
:param context: The RequestContext object
:param spec_obj: The RequestSpec object
:param instance_uuids: List of instance UUIDs to place or move.
:param alloc_reqs_by_rp_uuid: Optional dict, keyed by resource provider
UUID, of the allocation_requests that may be used to claim
resources against matched hosts. If None, indicates either the
placement API wasn't reachable or that there were no
allocation_requests returned by the placement API. If the latter,
the provider_summaries will be an empty dict, not None.
:param provider_summaries: Optional dict, keyed by resource provider
UUID, of information that will be used by the filters/weighers in
selecting matching hosts for a request. If None, indicates that the
scheduler driver should grab all compute node information locally
and that the Placement API is not used. If an empty dict, indicates
the Placement API returned no potential matches for the requested
resources.
:param allocation_request_version: The microversion used to request the
allocations.
:param return_alternates: When True, zero or more alternate hosts are
returned with each selected host. The number of alternates is
determined by the configuration option
`CONF.scheduler.max_attempts`.
"""
elevated = context.elevated()
# Find our local list of acceptable hosts by repeatedly
# filtering and weighing our options. Each time we choose a
# host, we virtually consume resources on it so subsequent
# selections can adjust accordingly.
# Note: remember, we are using a generator-iterator here. So only
# traverse this list once. This can bite you if the hosts
# are being scanned in a filter or weighing function.
hosts = self._get_all_host_states(
elevated, spec_obj, provider_summaries)
# NOTE(sbauza): The RequestSpec.num_instances field contains the number
# of instances created when the RequestSpec was used to first boot some
# instances. This is incorrect when doing a move or resize operation,
# so prefer the length of instance_uuids unless it is None.
num_instances = (len(instance_uuids) if instance_uuids
else spec_obj.num_instances)
# For each requested instance, we want to return a host whose resources
# for the instance have been claimed, along with zero or more
# alternates. These alternates will be passed to the cell that the
# selected host is in, so that if for some reason the build fails, the
# cell conductor can retry building the instance on one of these
# alternates instead of having to simply fail. The number of alternates
# is based on CONF.scheduler.max_attempts; note that if there are not
# enough filtered hosts to provide the full number of alternates, the
# list of hosts may be shorter than this amount.
num_alts = CONF.scheduler.max_attempts - 1 if return_alternates else 0
if instance_uuids is None or alloc_reqs_by_rp_uuid is None:
# If there was a problem communicating with the
# placement API, alloc_reqs_by_rp_uuid will be None, so we skip
# claiming in that case as well. In the case where instance_uuids
# is None, that indicates an older conductor, so we need to return
# the objects without alternates. They will be converted back to
# the older dict format representing HostState objects.
# TODO(stephenfin): Remove this when we bump scheduler the RPC API
# version to 5.0
return self._legacy_find_hosts(
context, num_instances, spec_obj, hosts, num_alts,
instance_uuids=instance_uuids)
# A list of the instance UUIDs that were successfully claimed against
# in the placement API. If we are not able to successfully claim for
# all involved instances, we use this list to remove those allocations
# before returning
claimed_instance_uuids = []
# The list of hosts that have been selected (and claimed).
claimed_hosts = []
for num, instance_uuid in enumerate(instance_uuids):
# In a multi-create request, the first request spec from the list
# is passed to the scheduler and that request spec's instance_uuid
# might not be the same as the instance we're processing, so we
# update the instance_uuid in that case before passing the request
# spec to filters since at least one filter
# (ServerGroupAntiAffinityFilter) depends on that information being
# accurate.
spec_obj.instance_uuid = instance_uuid
# Reset the field so it's not persisted accidentally.
spec_obj.obj_reset_changes(['instance_uuid'])
hosts = self._get_sorted_hosts(spec_obj, hosts, num)
if not hosts:
# NOTE(jaypipes): If we get here, that means not all instances
# in instance_uuids were able to be matched to a selected host.
# Any allocations will be cleaned up in the
# _ensure_sufficient_hosts() call.
break
# Attempt to claim the resources against one or more resource
# providers, looping over the sorted list of possible hosts
# looking for an allocation_request that contains that host's
# resource provider UUID
claimed_host = None
for host in hosts:
cn_uuid = host.uuid
if cn_uuid not in alloc_reqs_by_rp_uuid:
msg = ("A host state with uuid = '%s' that did not have a "
"matching allocation_request was encountered while "
"scheduling. This host was skipped.")
LOG.debug(msg, cn_uuid)
continue
alloc_reqs = alloc_reqs_by_rp_uuid[cn_uuid]
# TODO(jaypipes): Loop through all allocation_requests instead
# of just trying the first one. For now, since we'll likely
# want to order the allocation_requests in the future based on
# information in the provider summaries, we'll just try to
# claim resources using the first allocation_request
alloc_req = alloc_reqs[0]
if utils.claim_resources(
elevated, self.placement_client, spec_obj, instance_uuid,
alloc_req,
allocation_request_version=allocation_request_version,
):
claimed_host = host
break
if claimed_host is None:
# We weren't able to claim resources in the placement API
# for any of the sorted hosts identified. So, clean up any
# successfully-claimed resources for prior instances in
# this request and return an empty list which will cause
# select_destinations() to raise NoValidHost
LOG.debug("Unable to successfully claim against any host.")
break
claimed_instance_uuids.append(instance_uuid)
claimed_hosts.append(claimed_host)
# Now consume the resources so the filter/weights will change for
# the next instance.
self._consume_selected_host(
claimed_host, spec_obj, instance_uuid=instance_uuid)
# Check if we were able to fulfill the request. If not, this call will
# raise a NoValidHost exception.
self._ensure_sufficient_hosts(
context, claimed_hosts, num_instances, claimed_instance_uuids)
# We have selected and claimed hosts for each instance. Now we need to
# find alternates for each host.
return self._get_alternate_hosts(
claimed_hosts, spec_obj, hosts, num, num_alts,
alloc_reqs_by_rp_uuid, allocation_request_version)
def _ensure_sufficient_hosts(
self, context, hosts, required_count, claimed_uuids=None,
):
"""Checks that we have selected a host for each requested instance. If
not, log this failure, remove allocations for any claimed instances,
and raise a NoValidHost exception.
"""
if len(hosts) == required_count:
# We have enough hosts.
return
if claimed_uuids:
self._cleanup_allocations(context, claimed_uuids)
# NOTE(Rui Chen): If multiple creates failed, set the updated time
# of selected HostState to None so that these HostStates are
# refreshed according to database in next schedule, and release
# the resource consumed by instance in the process of selecting
# host.
for host in hosts:
host.updated = None
# Log the details but don't put those into the reason since
# we don't want to give away too much information about our
# actual environment.
LOG.debug(
'There are %(hosts)d hosts available but '
'%(required_count)d instances requested to build.',
{'hosts': len(hosts), 'required_count': required_count})
reason = _('There are not enough hosts available.')
raise exception.NoValidHost(reason=reason)
def _cleanup_allocations(self, context, instance_uuids):
"""Removes allocations for the supplied instance UUIDs."""
if not instance_uuids:
return
LOG.debug("Cleaning up allocations for %s", instance_uuids)
for uuid in instance_uuids:
self.placement_client.delete_allocation_for_instance(context, uuid)
def _legacy_find_hosts(
self, context, num_instances, spec_obj, hosts, num_alts,
instance_uuids=None,
):
"""Find hosts without invoking placement.
We may not be able to claim if the Placement service is not reachable.
Additionally, we may be working with older conductors that don't pass
in instance_uuids.
"""
# The list of hosts selected for each instance
selected_hosts = []
for num in range(num_instances):
instance_uuid = instance_uuids[num] if instance_uuids else None
if instance_uuid:
# Update the RequestSpec.instance_uuid before sending it to
# the filters in case we're doing a multi-create request, but
# don't persist the change.
spec_obj.instance_uuid = instance_uuid
spec_obj.obj_reset_changes(['instance_uuid'])
hosts = self._get_sorted_hosts(spec_obj, hosts, num)
if not hosts:
# No hosts left, so break here, and the
# _ensure_sufficient_hosts() call below will handle this.
break
selected_host = hosts[0]
selected_hosts.append(selected_host)
self._consume_selected_host(
selected_host, spec_obj, instance_uuid=instance_uuid)
# Check if we were able to fulfill the request. If not, this call will
# raise a NoValidHost exception.
self._ensure_sufficient_hosts(context, selected_hosts, num_instances)
# This the overall list of values to be returned. There will be one
# item per instance, and each item will be a list of Selection objects
# representing the selected host along with zero or more alternates
# from the same cell.
return self._get_alternate_hosts(
selected_hosts, spec_obj, hosts, num, num_alts)
@staticmethod
def _consume_selected_host(selected_host, spec_obj, instance_uuid=None):
LOG.debug(
"Selected host: %(host)s", {'host': selected_host},
instance_uuid=instance_uuid)
selected_host.consume_from_request(spec_obj)
# If we have a server group, add the selected host to it for the
# (anti-)affinity filters to filter out hosts for subsequent instances
# in a multi-create request.
if spec_obj.instance_group is not None:
spec_obj.instance_group.hosts.append(selected_host.host)
# hosts has to be not part of the updates when saving
spec_obj.instance_group.obj_reset_changes(['hosts'])
# The ServerGroupAntiAffinityFilter also relies on
# HostState.instances being accurate within a multi-create request.
if instance_uuid and instance_uuid not in selected_host.instances:
# Set a stub since ServerGroupAntiAffinityFilter only cares
# about the keys.
selected_host.instances[instance_uuid] = objects.Instance(
uuid=instance_uuid)
def _get_alternate_hosts(
self, selected_hosts, spec_obj, hosts, index, num_alts,
alloc_reqs_by_rp_uuid=None, allocation_request_version=None,
):
# We only need to filter/weigh the hosts again if we're dealing with
# more than one instance and are going to be picking alternates.
if index > 0 and num_alts > 0:
# The selected_hosts have all had resources 'claimed' via
# _consume_selected_host, so we need to filter/weigh and sort the
# hosts again to get an accurate count for alternates.
hosts = self._get_sorted_hosts(spec_obj, hosts, index)
# This is the overall list of values to be returned. There will be one
# item per instance, and each item will be a list of Selection objects
# representing the selected host along with alternates from the same
# cell.
selections_to_return = []
for selected_host in selected_hosts:
# This is the list of hosts for one particular instance.
if alloc_reqs_by_rp_uuid:
selected_alloc_req = alloc_reqs_by_rp_uuid.get(
selected_host.uuid)[0]
else:
selected_alloc_req = None
selection = objects.Selection.from_host_state(
selected_host, allocation_request=selected_alloc_req,
allocation_request_version=allocation_request_version)
selected_plus_alts = [selection]
cell_uuid = selected_host.cell_uuid
# This will populate the alternates with many of the same unclaimed
# hosts. This is OK, as it should be rare for a build to fail. And
# if there are not enough hosts to fully populate the alternates,
# it's fine to return fewer than we'd like. Note that we exclude
# any claimed host from consideration as an alternate because it
# will have had its resources reduced and will have a much lower
# chance of being able to fit another instance on it.
for host in hosts:
if len(selected_plus_alts) >= num_alts + 1:
break
if host.cell_uuid == cell_uuid and host not in selected_hosts:
if alloc_reqs_by_rp_uuid is not None:
alt_uuid = host.uuid
if alt_uuid not in alloc_reqs_by_rp_uuid:
msg = ("A host state with uuid = '%s' that did "
"not have a matching allocation_request "
"was encountered while scheduling. This "
"host was skipped.")
LOG.debug(msg, alt_uuid)
continue
# TODO(jaypipes): Loop through all allocation_requests
# instead of just trying the first one. For now, since
# we'll likely want to order the allocation_requests in
# the future based on information in the provider
# summaries, we'll just try to claim resources using
# the first allocation_request
alloc_req = alloc_reqs_by_rp_uuid[alt_uuid][0]
alt_selection = objects.Selection.from_host_state(
host, alloc_req, allocation_request_version)
else:
alt_selection = objects.Selection.from_host_state(host)
selected_plus_alts.append(alt_selection)
selections_to_return.append(selected_plus_alts)
return selections_to_return
def _get_sorted_hosts(self, spec_obj, host_states, index):
"""Returns a list of HostState objects that match the required
scheduling constraints for the request spec object and have been sorted
according to the weighers.
"""
filtered_hosts = self.host_manager.get_filtered_hosts(host_states,
spec_obj, index)
LOG.debug("Filtered %(hosts)s", {'hosts': filtered_hosts})
if not filtered_hosts:
return []
weighed_hosts = self.host_manager.get_weighed_hosts(
filtered_hosts, spec_obj)
if CONF.filter_scheduler.shuffle_best_same_weighed_hosts:
# NOTE(pas-ha) Randomize best hosts, relying on weighed_hosts
# being already sorted by weight in descending order.
# This decreases possible contention and rescheduling attempts
# when there is a large number of hosts having the same best
# weight, especially so when host_subset_size is 1 (default)
best_hosts = [
w for w in weighed_hosts
if w.weight == weighed_hosts[0].weight
]
random.shuffle(best_hosts)
weighed_hosts = best_hosts + weighed_hosts[len(best_hosts):]
# Log the weighed hosts before stripping off the wrapper class so that
# the weight value gets logged.
LOG.debug("Weighed %(hosts)s", {'hosts': weighed_hosts})
# Strip off the WeighedHost wrapper class...
weighed_hosts = [h.obj for h in weighed_hosts]
# We randomize the first element in the returned list to alleviate
# congestion where the same host is consistently selected among
# numerous potential hosts for similar request specs.
host_subset_size = CONF.filter_scheduler.host_subset_size
if host_subset_size < len(weighed_hosts):
weighed_subset = weighed_hosts[0:host_subset_size]
else:
weighed_subset = weighed_hosts
chosen_host = random.choice(weighed_subset)
weighed_hosts.remove(chosen_host)
return [chosen_host] + weighed_hosts
def _get_all_host_states(self, context, spec_obj, provider_summaries):
"""Template method, so a subclass can implement caching."""
# The provider_summaries variable will be an empty dict when the
# Placement API found no providers that match the requested
# constraints, which in turn makes compute_uuids an empty list and
# get_host_states_by_uuids will return an empty generator-iterator
# also, which will eventually result in a NoValidHost error.
compute_uuids = None
if provider_summaries is not None:
compute_uuids = list(provider_summaries.keys())
return self.host_manager.get_host_states_by_uuids(
context, compute_uuids, spec_obj)

572
nova/scheduler/manager.py
View File

@ -20,27 +20,31 @@ Scheduler Service
"""
import collections
import random
from oslo_log import log as logging
import oslo_messaging as messaging
from oslo_serialization import jsonutils
from oslo_service import periodic_task
from nova.compute import utils as compute_utils
import nova.conf
from nova import exception
from nova.i18n import _
from nova import manager
from nova import objects
from nova.objects import fields as fields_obj
from nova.objects import host_mapping as host_mapping_obj
from nova import quota
from nova import rpc
from nova.scheduler.client import report
from nova.scheduler import driver
from nova.scheduler import host_manager
from nova.scheduler import request_filter
from nova.scheduler import utils
LOG = logging.getLogger(__name__)
from nova import servicegroup
CONF = nova.conf.CONF
LOG = logging.getLogger(__name__)
QUOTAS = quota.QUOTAS
@ -48,19 +52,23 @@ HOST_MAPPING_EXISTS_WARNING = False
class SchedulerManager(manager.Manager):
"""Chooses a host to run instances on."""
"""Chooses a host to run instances on.
Filters and weighs compute hosts to determine the best host to schedule an
instance to.
"""
target = messaging.Target(version='4.5')
_sentinel = object()
def __init__(self, *args, **kwargs):
self.host_manager = host_manager.HostManager()
self.servicegroup_api = servicegroup.API()
self.notifier = rpc.get_notifier('scheduler')
self.placement_client = report.SchedulerReportClient()
self.driver = driver.SchedulerDriver()
super(SchedulerManager, self).__init__(
service_name='scheduler', *args, **kwargs
)
super().__init__(service_name='scheduler', *args, **kwargs)
@periodic_task.periodic_task(
spacing=CONF.scheduler.discover_hosts_in_cells_interval,
@ -70,15 +78,22 @@ class SchedulerManager(manager.Manager):
try:
host_mappings = host_mapping_obj.discover_hosts(context)
if host_mappings:
LOG.info('Discovered %(count)i new hosts: %(hosts)s',
{'count': len(host_mappings),
'hosts': ','.join(['%s:%s' % (hm.cell_mapping.name,
hm.host)
for hm in host_mappings])})
LOG.info(
'Discovered %(count)i new hosts: %(hosts)s',
{
'count': len(host_mappings),
'hosts': ','.join([
'%s:%s' % (hm.cell_mapping.name, hm.host)
for hm in host_mappings
]),
},
)
except exception.HostMappingExists as exp:
msg = ('This periodic task should only be enabled on a single '
'scheduler to prevent collisions between multiple '
'schedulers: %s' % str(exp))
msg = (
'This periodic task should only be enabled on a single '
'scheduler to prevent collisions between multiple '
'schedulers: %s' % str(exp)
)
if not HOST_MAPPING_EXISTS_WARNING:
LOG.warning(msg)
HOST_MAPPING_EXISTS_WARNING = True
@ -93,12 +108,14 @@ class SchedulerManager(manager.Manager):
# NOTE(mriedem): Similarly there is a host-to-cell cache which should
# be reset if a host is deleted from a cell and "discovered" in another
# cell.
self.driver.host_manager.refresh_cells_caches()
self.host_manager.refresh_cells_caches()
@messaging.expected_exceptions(exception.NoValidHost)
def select_destinations(self, ctxt, request_spec=None,
filter_properties=None, spec_obj=_sentinel, instance_uuids=None,
return_objects=False, return_alternates=False):
def select_destinations(
self, context, request_spec=None,
filter_properties=None, spec_obj=_sentinel, instance_uuids=None,
return_objects=False, return_alternates=False,
):
"""Returns destinations(s) best suited for this RequestSpec.
Starting in Queens, this method returns a list of lists of Selection
@ -126,24 +143,23 @@ class SchedulerManager(manager.Manager):
# TODO(sbauza): Change the method signature to only accept a spec_obj
# argument once API v5 is provided.
if spec_obj is self._sentinel:
spec_obj = objects.RequestSpec.from_primitives(ctxt,
request_spec,
filter_properties)
spec_obj = objects.RequestSpec.from_primitives(
context, request_spec, filter_properties)
is_rebuild = utils.request_is_rebuild(spec_obj)
alloc_reqs_by_rp_uuid, provider_summaries, allocation_request_version \
= None, None, None
if not is_rebuild:
try:
request_filter.process_reqspec(ctxt, spec_obj)
request_filter.process_reqspec(context, spec_obj)
except exception.RequestFilterFailed as e:
raise exception.NoValidHost(reason=e.message)
resources = utils.resources_from_request_spec(
ctxt, spec_obj, self.driver.host_manager,
context, spec_obj, self.host_manager,
enable_pinning_translate=True)
res = self.placement_client.get_allocation_candidates(ctxt,
resources)
res = self.placement_client.get_allocation_candidates(
context, resources)
if res is None:
# We have to handle the case that we failed to connect to the
# Placement service and the safe_connect decorator on
@ -163,15 +179,19 @@ class SchedulerManager(manager.Manager):
# weed out hosts that are actually using new style configuration
# but simply don't have enough free PCPUs (or any PCPUs).
# TODO(stephenfin): Remove when we drop support for 'vcpu_pin_set'
if (resources.cpu_pinning_requested and
not CONF.workarounds.disable_fallback_pcpu_query):
LOG.debug('Requesting fallback allocation candidates with '
'VCPU instead of PCPU')
if (
resources.cpu_pinning_requested and
not CONF.workarounds.disable_fallback_pcpu_query
):
LOG.debug(
'Requesting fallback allocation candidates with '
'VCPU instead of PCPU'
)
resources = utils.resources_from_request_spec(
ctxt, spec_obj, self.driver.host_manager,
context, spec_obj, self.host_manager,
enable_pinning_translate=False)
res = self.placement_client.get_allocation_candidates(
ctxt, resources)
context, resources)
if res:
# merge the allocation requests and provider summaries from
# the two requests together
@ -181,42 +201,472 @@ class SchedulerManager(manager.Manager):
provider_summaries.update(provider_summaries_fallback)
if not alloc_reqs:
LOG.info("Got no allocation candidates from the Placement "
"API. This could be due to insufficient resources "
"or a temporary occurrence as compute nodes start "
"up.")
LOG.info(
"Got no allocation candidates from the Placement API. "
"This could be due to insufficient resources or a "
"temporary occurrence as compute nodes start up."
)
raise exception.NoValidHost(reason="")
else:
# Build a dict of lists of allocation requests, keyed by
# provider UUID, so that when we attempt to claim resources for
# a host, we can grab an allocation request easily
alloc_reqs_by_rp_uuid = collections.defaultdict(list)
for ar in alloc_reqs:
for rp_uuid in ar['allocations']:
alloc_reqs_by_rp_uuid[rp_uuid].append(ar)
# Build a dict of lists of allocation requests, keyed by
# provider UUID, so that when we attempt to claim resources for
# a host, we can grab an allocation request easily
alloc_reqs_by_rp_uuid = collections.defaultdict(list)
for ar in alloc_reqs:
for rp_uuid in ar['allocations']:
alloc_reqs_by_rp_uuid[rp_uuid].append(ar)
# Only return alternates if both return_objects and return_alternates
# are True.
return_alternates = return_alternates and return_objects
selections = self.driver.select_destinations(ctxt, spec_obj,
instance_uuids, alloc_reqs_by_rp_uuid, provider_summaries,
allocation_request_version, return_alternates)
selections = self._select_destinations(
context, spec_obj, instance_uuids, alloc_reqs_by_rp_uuid,
provider_summaries, allocation_request_version, return_alternates)
# If `return_objects` is False, we need to convert the selections to
# the older format, which is a list of host state dicts.
if not return_objects:
selection_dicts = [sel[0].to_dict() for sel in selections]
return jsonutils.to_primitive(selection_dicts)
return selections
def _select_destinations(
self, context, spec_obj, instance_uuids,
alloc_reqs_by_rp_uuid, provider_summaries,
allocation_request_version=None, return_alternates=False,
):
self.notifier.info(
context, 'scheduler.select_destinations.start',
{'request_spec': spec_obj.to_legacy_request_spec_dict()})
compute_utils.notify_about_scheduler_action(
context=context, request_spec=spec_obj,
action=fields_obj.NotificationAction.SELECT_DESTINATIONS,
phase=fields_obj.NotificationPhase.START)
# Only return alternates if both return_objects and return_alternates
# are True.
selections = self._schedule(
context, spec_obj, instance_uuids,
alloc_reqs_by_rp_uuid, provider_summaries,
allocation_request_version, return_alternates)
self.notifier.info(
context, 'scheduler.select_destinations.end',
{'request_spec': spec_obj.to_legacy_request_spec_dict()})
compute_utils.notify_about_scheduler_action(
context=context, request_spec=spec_obj,
action=fields_obj.NotificationAction.SELECT_DESTINATIONS,
phase=fields_obj.NotificationPhase.END)
return selections
def _schedule(
self, context, spec_obj, instance_uuids, alloc_reqs_by_rp_uuid,
provider_summaries, allocation_request_version=None,
return_alternates=False
):
"""Returns a list of lists of Selection objects.
:param context: The RequestContext object
:param spec_obj: The RequestSpec object
:param instance_uuids: List of instance UUIDs to place or move.
:param alloc_reqs_by_rp_uuid: Optional dict, keyed by resource provider
UUID, of the allocation_requests that may be used to claim
resources against matched hosts. If None, indicates either the
placement API wasn't reachable or that there were no
allocation_requests returned by the placement API. If the latter,
the provider_summaries will be an empty dict, not None.
:param provider_summaries: Optional dict, keyed by resource provider
UUID, of information that will be used by the filters/weighers in
selecting matching hosts for a request. If None, indicates that
we should grab all compute node information locally
and that the Placement API is not used. If an empty dict, indicates
the Placement API returned no potential matches for the requested
resources.
:param allocation_request_version: The microversion used to request the
allocations.
:param return_alternates: When True, zero or more alternate hosts are
returned with each selected host. The number of alternates is
determined by the configuration option
`CONF.scheduler.max_attempts`.
"""
elevated = context.elevated()
# Find our local list of acceptable hosts by repeatedly
# filtering and weighing our options. Each time we choose a
# host, we virtually consume resources on it so subsequent
# selections can adjust accordingly.
# Note: remember, we are using a generator-iterator here. So only
# traverse this list once. This can bite you if the hosts
# are being scanned in a filter or weighing function.
hosts = self._get_all_host_states(
elevated, spec_obj, provider_summaries)
# NOTE(sbauza): The RequestSpec.num_instances field contains the number
# of instances created when the RequestSpec was used to first boot some
# instances. This is incorrect when doing a move or resize operation,
# so prefer the length of instance_uuids unless it is None.
num_instances = (len(instance_uuids) if instance_uuids
else spec_obj.num_instances)
# For each requested instance, we want to return a host whose resources
# for the instance have been claimed, along with zero or more
# alternates. These alternates will be passed to the cell that the
# selected host is in, so that if for some reason the build fails, the
# cell conductor can retry building the instance on one of these
# alternates instead of having to simply fail. The number of alternates
# is based on CONF.scheduler.max_attempts; note that if there are not
# enough filtered hosts to provide the full number of alternates, the
# list of hosts may be shorter than this amount.
num_alts = CONF.scheduler.max_attempts - 1 if return_alternates else 0
if instance_uuids is None or alloc_reqs_by_rp_uuid is None:
# If there was a problem communicating with the
# placement API, alloc_reqs_by_rp_uuid will be None, so we skip
# claiming in that case as well. In the case where instance_uuids
# is None, that indicates an older conductor, so we need to return
# the objects without alternates. They will be converted back to
# the older dict format representing HostState objects.
# TODO(stephenfin): Remove this when we bump scheduler the RPC API
# version to 5.0
return self._legacy_find_hosts(
context, num_instances, spec_obj, hosts, num_alts,
instance_uuids=instance_uuids)
# A list of the instance UUIDs that were successfully claimed against
# in the placement API. If we are not able to successfully claim for
# all involved instances, we use this list to remove those allocations
# before returning
claimed_instance_uuids = []
# The list of hosts that have been selected (and claimed).
claimed_hosts = []
for num, instance_uuid in enumerate(instance_uuids):
# In a multi-create request, the first request spec from the list
# is passed to the scheduler and that request spec's instance_uuid
# might not be the same as the instance we're processing, so we
# update the instance_uuid in that case before passing the request
# spec to filters since at least one filter
# (ServerGroupAntiAffinityFilter) depends on that information being
# accurate.
spec_obj.instance_uuid = instance_uuid
# Reset the field so it's not persisted accidentally.
spec_obj.obj_reset_changes(['instance_uuid'])
hosts = self._get_sorted_hosts(spec_obj, hosts, num)
if not hosts:
# NOTE(jaypipes): If we get here, that means not all instances
# in instance_uuids were able to be matched to a selected host.
# Any allocations will be cleaned up in the
# _ensure_sufficient_hosts() call.
break
# Attempt to claim the resources against one or more resource
# providers, looping over the sorted list of possible hosts
# looking for an allocation_request that contains that host's
# resource provider UUID
claimed_host = None
for host in hosts:
cn_uuid = host.uuid
if cn_uuid not in alloc_reqs_by_rp_uuid:
msg = ("A host state with uuid = '%s' that did not have a "
"matching allocation_request was encountered while "
"scheduling. This host was skipped.")
LOG.debug(msg, cn_uuid)
continue
alloc_reqs = alloc_reqs_by_rp_uuid[cn_uuid]
# TODO(jaypipes): Loop through all allocation_requests instead
# of just trying the first one. For now, since we'll likely
# want to order the allocation_requests in the future based on
# information in the provider summaries, we'll just try to
# claim resources using the first allocation_request
alloc_req = alloc_reqs[0]
if utils.claim_resources(
elevated, self.placement_client, spec_obj, instance_uuid,
alloc_req,
allocation_request_version=allocation_request_version,
):
claimed_host = host
break
if claimed_host is None:
# We weren't able to claim resources in the placement API
# for any of the sorted hosts identified. So, clean up any
# successfully-claimed resources for prior instances in
# this request and return an empty list which will cause
# select_destinations() to raise NoValidHost
LOG.debug("Unable to successfully claim against any host.")
break
claimed_instance_uuids.append(instance_uuid)
claimed_hosts.append(claimed_host)
# Now consume the resources so the filter/weights will change for
# the next instance.
self._consume_selected_host(
claimed_host, spec_obj, instance_uuid=instance_uuid)
# Check if we were able to fulfill the request. If not, this call will
# raise a NoValidHost exception.
self._ensure_sufficient_hosts(
context, claimed_hosts, num_instances, claimed_instance_uuids)
# We have selected and claimed hosts for each instance. Now we need to
# find alternates for each host.
return self._get_alternate_hosts(
claimed_hosts, spec_obj, hosts, num, num_alts,
alloc_reqs_by_rp_uuid, allocation_request_version)
def _ensure_sufficient_hosts(
self, context, hosts, required_count, claimed_uuids=None,
):
"""Checks that we have selected a host for each requested instance. If
not, log this failure, remove allocations for any claimed instances,
and raise a NoValidHost exception.
"""
if len(hosts) == required_count:
# We have enough hosts.
return
if claimed_uuids:
self._cleanup_allocations(context, claimed_uuids)
# NOTE(Rui Chen): If multiple creates failed, set the updated time
# of selected HostState to None so that these HostStates are
# refreshed according to database in next schedule, and release
# the resource consumed by instance in the process of selecting
# host.
for host in hosts:
host.updated = None
# Log the details but don't put those into the reason since
# we don't want to give away too much information about our
# actual environment.
LOG.debug(
'There are %(hosts)d hosts available but '
'%(required_count)d instances requested to build.',
{'hosts': len(hosts), 'required_count': required_count})
reason = _('There are not enough hosts available.')
raise exception.NoValidHost(reason=reason)
def _cleanup_allocations(self, context, instance_uuids):
"""Removes allocations for the supplied instance UUIDs."""
if not instance_uuids:
return
LOG.debug("Cleaning up allocations for %s", instance_uuids)
for uuid in instance_uuids:
self.placement_client.delete_allocation_for_instance(context, uuid)
def _legacy_find_hosts(
self, context, num_instances, spec_obj, hosts, num_alts,
instance_uuids=None,
):
"""Find hosts without invoking placement.
We may not be able to claim if the Placement service is not reachable.
Additionally, we may be working with older conductors that don't pass
in instance_uuids.
"""
# The list of hosts selected for each instance
selected_hosts = []
for num in range(num_instances):
instance_uuid = instance_uuids[num] if instance_uuids else None
if instance_uuid:
# Update the RequestSpec.instance_uuid before sending it to
# the filters in case we're doing a multi-create request, but
# don't persist the change.
spec_obj.instance_uuid = instance_uuid
spec_obj.obj_reset_changes(['instance_uuid'])
hosts = self._get_sorted_hosts(spec_obj, hosts, num)
if not hosts:
# No hosts left, so break here, and the
# _ensure_sufficient_hosts() call below will handle this.
break
selected_host = hosts[0]
selected_hosts.append(selected_host)
self._consume_selected_host(
selected_host, spec_obj, instance_uuid=instance_uuid)
# Check if we were able to fulfill the request. If not, this call will
# raise a NoValidHost exception.
self._ensure_sufficient_hosts(context, selected_hosts, num_instances)
# This the overall list of values to be returned. There will be one
# item per instance, and each item will be a list of Selection objects
# representing the selected host along with zero or more alternates
# from the same cell.
return self._get_alternate_hosts(
selected_hosts, spec_obj, hosts, num, num_alts)
@staticmethod
def _consume_selected_host(selected_host, spec_obj, instance_uuid=None):
LOG.debug(
"Selected host: %(host)s", {'host': selected_host},
instance_uuid=instance_uuid)
selected_host.consume_from_request(spec_obj)
# If we have a server group, add the selected host to it for the
# (anti-)affinity filters to filter out hosts for subsequent instances
# in a multi-create request.
if spec_obj.instance_group is not None:
spec_obj.instance_group.hosts.append(selected_host.host)
# hosts has to be not part of the updates when saving
spec_obj.instance_group.obj_reset_changes(['hosts'])
# The ServerGroupAntiAffinityFilter also relies on
# HostState.instances being accurate within a multi-create request.
if instance_uuid and instance_uuid not in selected_host.instances:
# Set a stub since ServerGroupAntiAffinityFilter only cares
# about the keys.
selected_host.instances[instance_uuid] = objects.Instance(
uuid=instance_uuid)
def _get_alternate_hosts(
self, selected_hosts, spec_obj, hosts, index, num_alts,
alloc_reqs_by_rp_uuid=None, allocation_request_version=None,
):
# We only need to filter/weigh the hosts again if we're dealing with
# more than one instance and are going to be picking alternates.
if index > 0 and num_alts > 0:
# The selected_hosts have all had resources 'claimed' via
# _consume_selected_host, so we need to filter/weigh and sort the
# hosts again to get an accurate count for alternates.
hosts = self._get_sorted_hosts(spec_obj, hosts, index)
# This is the overall list of values to be returned. There will be one
# item per instance, and each item will be a list of Selection objects
# representing the selected host along with alternates from the same
# cell.
selections_to_return = []
for selected_host in selected_hosts:
# This is the list of hosts for one particular instance.
if alloc_reqs_by_rp_uuid:
selected_alloc_req = alloc_reqs_by_rp_uuid.get(
selected_host.uuid)[0]
else:
selected_alloc_req = None
selection = objects.Selection.from_host_state(
selected_host, allocation_request=selected_alloc_req,
allocation_request_version=allocation_request_version)
selected_plus_alts = [selection]
cell_uuid = selected_host.cell_uuid
# This will populate the alternates with many of the same unclaimed
# hosts. This is OK, as it should be rare for a build to fail. And
# if there are not enough hosts to fully populate the alternates,
# it's fine to return fewer than we'd like. Note that we exclude
# any claimed host from consideration as an alternate because it
# will have had its resources reduced and will have a much lower
# chance of being able to fit another instance on it.
for host in hosts:
if len(selected_plus_alts) >= num_alts + 1:
break
if host.cell_uuid == cell_uuid and host not in selected_hosts:
if alloc_reqs_by_rp_uuid is not None:
alt_uuid = host.uuid
if alt_uuid not in alloc_reqs_by_rp_uuid:
msg = ("A host state with uuid = '%s' that did "
"not have a matching allocation_request "
"was encountered while scheduling. This "
"host was skipped.")
LOG.debug(msg, alt_uuid)
continue
# TODO(jaypipes): Loop through all allocation_requests
# instead of just trying the first one. For now, since
# we'll likely want to order the allocation_requests in
# the future based on information in the provider
# summaries, we'll just try to claim resources using
# the first allocation_request
alloc_req = alloc_reqs_by_rp_uuid[alt_uuid][0]
alt_selection = objects.Selection.from_host_state(
host, alloc_req, allocation_request_version)
else:
alt_selection = objects.Selection.from_host_state(host)
selected_plus_alts.append(alt_selection)
selections_to_return.append(selected_plus_alts)
return selections_to_return
def _get_sorted_hosts(self, spec_obj, host_states, index):
"""Returns a list of HostState objects that match the required
scheduling constraints for the request spec object and have been sorted
according to the weighers.
"""
filtered_hosts = self.host_manager.get_filtered_hosts(host_states,
spec_obj, index)
LOG.debug("Filtered %(hosts)s", {'hosts': filtered_hosts})
if not filtered_hosts:
return []
weighed_hosts = self.host_manager.get_weighed_hosts(
filtered_hosts, spec_obj)
if CONF.filter_scheduler.shuffle_best_same_weighed_hosts:
# NOTE(pas-ha) Randomize best hosts, relying on weighed_hosts
# being already sorted by weight in descending order.
# This decreases possible contention and rescheduling attempts
# when there is a large number of hosts having the same best
# weight, especially so when host_subset_size is 1 (default)
best_hosts = [
w for w in weighed_hosts
if w.weight == weighed_hosts[0].weight
]
random.shuffle(best_hosts)
weighed_hosts = best_hosts + weighed_hosts[len(best_hosts):]
# Log the weighed hosts before stripping off the wrapper class so that
# the weight value gets logged.
LOG.debug("Weighed %(hosts)s", {'hosts': weighed_hosts})
# Strip off the WeighedHost wrapper class...
weighed_hosts = [h.obj for h in weighed_hosts]
# We randomize the first element in the returned list to alleviate
# congestion where the same host is consistently selected among
# numerous potential hosts for similar request specs.
host_subset_size = CONF.filter_scheduler.host_subset_size
if host_subset_size < len(weighed_hosts):
weighed_subset = weighed_hosts[0:host_subset_size]
else:
weighed_subset = weighed_hosts
chosen_host = random.choice(weighed_subset)
weighed_hosts.remove(chosen_host)
return [chosen_host] + weighed_hosts
def _get_all_host_states(self, context, spec_obj, provider_summaries):
"""Template method, so a subclass can implement caching."""
# The provider_summaries variable will be an empty dict when the
# Placement API found no providers that match the requested
# constraints, which in turn makes compute_uuids an empty list and
# get_host_states_by_uuids will return an empty generator-iterator
# also, which will eventually result in a NoValidHost error.
compute_uuids = None
if provider_summaries is not None:
compute_uuids = list(provider_summaries.keys())
return self.host_manager.get_host_states_by_uuids(
context, compute_uuids, spec_obj)
def update_aggregates(self, ctxt, aggregates):
"""Updates HostManager internal aggregates information.
:param aggregates: Aggregate(s) to update
:type aggregates: :class:`nova.objects.Aggregate`
or :class:`nova.objects.AggregateList`
or :class:`nova.objects.AggregateList`
"""
# NOTE(sbauza): We're dropping the user context now as we don't need it
self.driver.host_manager.update_aggregates(aggregates)
self.host_manager.update_aggregates(aggregates)
def delete_aggregate(self, ctxt, aggregate):
"""Deletes HostManager internal information about a specific aggregate.
@ -225,25 +675,25 @@ class SchedulerManager(manager.Manager):
:type aggregate: :class:`nova.objects.Aggregate`
"""
# NOTE(sbauza): We're dropping the user context now as we don't need it
self.driver.host_manager.delete_aggregate(aggregate)
self.host_manager.delete_aggregate(aggregate)
def update_instance_info(self, context, host_name, instance_info):
"""Receives information about changes to a host's instances, and
updates the driver's HostManager with that information.
updates the HostManager with that information.
"""
self.driver.host_manager.update_instance_info(context, host_name,
instance_info)
self.host_manager.update_instance_info(
context, host_name, instance_info)
def delete_instance_info(self, context, host_name, instance_uuid):
"""Receives information about the deletion of one of a host's
instances, and updates the driver's HostManager with that information.
instances, and updates the HostManager with that information.
"""
self.driver.host_manager.delete_instance_info(context, host_name,
instance_uuid)
self.host_manager.delete_instance_info(
context, host_name, instance_uuid)
def sync_instance_info(self, context, host_name, instance_uuids):
"""Receives a sync request from a host, and passes it on to the
driver's HostManager.
HostManager.
"""
self.driver.host_manager.sync_instance_info(context, host_name,
instance_uuids)
self.host_manager.sync_instance_info(
context, host_name, instance_uuids)

2
nova/tests/functional/libvirt/test_numa_servers.py
View File

@ -42,7 +42,7 @@ class NUMAServersTestBase(base.ServersTestBase):
# Mock the 'NUMATopologyFilter' filter, as most tests need to inspect
# this
host_manager = self.scheduler.manager.driver.host_manager
host_manager = self.scheduler.manager.host_manager
numa_filter_class = host_manager.filter_cls_map['NUMATopologyFilter']
host_pass_mock = mock.Mock(wraps=numa_filter_class().host_passes)
_p = mock.patch('nova.scheduler.filters'

2
nova/tests/functional/libvirt/test_pci_sriov_servers.py
View File

@ -54,7 +54,7 @@ class _PCIServersTestBase(base.ServersTestBase):
# Mock the 'PciPassthroughFilter' filter, as most tests need to inspect
# this
host_manager = self.scheduler.manager.driver.host_manager
host_manager = self.scheduler.manager.host_manager
pci_filter_class = host_manager.filter_cls_map['PciPassthroughFilter']
host_pass_mock = mock.Mock(wraps=pci_filter_class().host_passes)
self.mock_filter = self.useFixture(fixtures.MockPatch(

8
nova/tests/functional/regressions/test_bug_1781710.py
View File

@ -10,7 +10,7 @@
# License for the specific language governing permissions and limitations
# under the License.
from nova.scheduler import driver as scheduler_driver
from nova.scheduler import manager as scheduler_manager
from nova import test
from nova.tests import fixtures as nova_fixtures
from nova.tests.functional import fixtures as func_fixtures
@ -71,11 +71,11 @@ class AntiAffinityMultiCreateRequest(test.TestCase,
group = self.api.post_server_groups(
{'name': 'test group', 'policy': 'anti-affinity'})
# Stub out Scheduler._get_alternate_hosts so we can assert what
# Stub out SchedulerManager._get_alternate_hosts so we can assert what
# is coming back for alternate hosts is what we'd expect after the
# initial hosts are selected for each instance.
original_get_alternate_hosts = (
scheduler_driver.SchedulerDriver._get_alternate_hosts)
scheduler_manager.SchedulerManager._get_alternate_hosts)
def stub_get_alternate_hosts(*a, **kw):
# Intercept the result so we can assert there are no alternates.
@ -96,7 +96,7 @@ class AntiAffinityMultiCreateRequest(test.TestCase,
return selections_to_return
self.stub_out(
'nova.scheduler.driver.SchedulerDriver._get_alternate_hosts',
'nova.scheduler.manager.SchedulerManager._get_alternate_hosts',
stub_get_alternate_hosts)
# Now create two servers in that group.

2
nova/tests/functional/test_servers.py
View File

@ -3654,7 +3654,7 @@ class ServerDeleteBuildTests(integrated_helpers.ProviderUsageBaseTestCase):
networks='none')
with test.nested(
mock.patch('nova.scheduler.driver.SchedulerDriver'
mock.patch('nova.scheduler.manager.SchedulerManager'
'._ensure_sufficient_hosts'),
mock.patch('nova.conductor.manager.ComputeTaskManager'
'._bury_in_cell0'),

1126
nova/tests/unit/scheduler/test_driver.py
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1173
nova/tests/unit/scheduler/test_manager.py
View File

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