AAP-68024 perf: derive last_job_host_summary from query instead of denormalized FK (#16332)

* perf: stop eagerly updating Host.last_job_host_summary on every job completion

The playbook_on_stats wrapup path bulk-updates last_job_host_summary_id
on every host touched by a job. In the Q4CY25 scale lab this query had
a median execution time of 75 seconds due to index churn on main_host.

Replace all reads of the denormalized FK with a new classmethod
JobHostSummary.latest_for_host(host_id) that queries for the most
recent summary on demand. This eliminates the write-side bulk_update
of last_job_host_summary_id entirely.

Changes:
- Add JobHostSummary.latest_for_host() classmethod
- Serializer: use latest_for_host() instead of obj.last_job_host_summary
- Dashboard view: use subquery instead of FK traversal for failed hosts
- Inventory.update_computed_fields: use subquery for failed host count
- events.py: remove last_job_host_summary_id from bulk_update
- signals.py: simplify _update_host_last_jhs to only update last_job
- access.py/managers.py: remove select_related/defer through the FK

The FK field on Host is left in place for now (removal requires a
migration) but is no longer written to.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Fix .pk AttributeError, add job_template annotations, annotate host sublists

- Add 'pk' to AnnotatedSummary dynamic type (fixes AttributeError in get_related)
- Add job_template_id and job_template_name to subquery annotations so list
  views include these fields in summary_fields.last_job (matching detail views)
- Traverse job__ FK from JobHostSummary instead of using separate UnifiedJob
  subquery with OuterRef on another annotation (cleaner SQL, avoids alias issue)
- Annotate all host sublist views (InventoryHostsList, GroupHostsList,
  GroupAllHostsList, InventorySourceHostsList) to prevent N+1 queries

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Update test_events to use JobHostSummary.latest_for_host instead of stale FKs

Tests were asserting host.last_job_id and host.last_job_host_summary_id
which are no longer updated. Use JobHostSummary.latest_for_host() to
derive the same data, matching the new read-time derivation approach.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Remove stale failures_url from deprecated DashboardView

The failures_url linked to ?last_job_host_summary__failed=True which
filters on the now-stale FK. The dashboard count itself was already
fixed to use a subquery annotation. Since DashboardView is deprecated
and has_active_failures is a SerializerMethodField (not filterable),
remove the failures_url entirely rather than creating a custom filter.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Apply black formatting to changed files

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Refactor: replace 10 subquery annotations with bulk prefetch

Instead of annotating every host queryset with 10 correlated subqueries
(summary + job + job_template fields), annotate only _latest_summary_id
and bulk-fetch the full JobHostSummary objects after pagination via
select_related('job', 'job__job_template').

This reduces the SQL from 10 correlated subqueries to 1 subquery + 1 IN
query, addressing review feedback about annotation overhead on host list
views.

- _annotate_host_latest_summary: only annotates _latest_summary_id
- _prefetch_latest_summaries: bulk-fetches and attaches to host objects
- HostSummaryPrefetchMixin: hooks into list() after pagination
- Serializer uses real JobHostSummary objects (no more AnnotatedSummary)
- to_representation always overwrites stale FK values

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Refactor: move latest summary to QuerySet._fetch_all + Host.latest_summary

Per review feedback, replace the view-level HostSummaryPrefetchMixin
with a custom QuerySet that bulk-attaches summaries at evaluation time
(like prefetch_related), and a Host.latest_summary property as the
single access point.

- HostLatestSummaryQuerySet: overrides _fetch_all() to bulk-fetch
  JobHostSummary objects with select_related after queryset evaluation
- HostManager now inherits from the custom queryset via from_queryset()
- Host.latest_summary property: uses cache if available, falls back to
  individual query
- Remove _annotate_host_latest_summary, _prefetch_latest_summaries,
  HostSummaryPrefetchMixin from views — no more list() override needed
- Remove last_job/last_job_host_summary from SUMMARIZABLE_FK_FIELDS
- Serializer uses obj.latest_summary and DEFAULT_SUMMARY_FIELDS loop

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Fix: scope annotation to views, restore license_error/canceled_on

- Remove with_latest_summary_id() from HostManager.get_queryset() to
  avoid applying the correlated subquery to every Host query globally
  (count, exists, internal relations)
- Apply with_latest_summary_id() in get_queryset() of the 6
  host-serving views only
- Restore license_error and canceled_on to last_job summary fields
  to avoid breaking API change

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Guard _fetch_all() to skip bulk-attach on non-annotated querysets

Without this guard, _fetch_all() would set _latest_summary_cache=None
on every host in non-annotated querysets (e.g. Host.objects.filter()),
masking the per-object fallback query in Host.latest_summary.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Remove name from last_job_host_summary and canceled_on from last_job summary

Per reviewer feedback: these fields were not in the original API contract
via SUMMARIZABLE_FK_FIELDS and their addition would be an API change.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Add functional tests for HostLatestSummaryQuerySet and Host.latest_summary

Tests cover:
- with_latest_summary_id() annotation and most-recent selection
- _fetch_all() bulk-attach behavior on annotated querysets
- _fetch_all() skips non-annotated querysets (preserves fallback)
- .count() and .exists() do NOT trigger _fetch_all
- Host.latest_summary cache hits (zero queries) and fallback
- Host.latest_job property
- select_related on bulk-attached summaries (no N+1)
- Chaining preserves annotation
- Multiple jobs / partial host coverage

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Apply black formatting to test_host_queryset.py

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Ben Thomasson <bthomass@redhat.com>

* Fix flake8 F841: remove unused job1/job2 variables in tests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Ben Thomasson <bthomass@redhat.com>

* Add comment explaining why Prefetch was not used for host latest summary

Django Prefetch cannot handle latest per group -- [:1] slicing fetches
1 record globally, not per host (Django ticket #26780). The custom
_fetch_all override uses the same 2-query pattern as prefetch_related
internally, customized for this use case.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Fix null handling to keep old behavior

---------

Signed-off-by: Ben Thomasson <bthomass@redhat.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: AlanCoding <arominge@redhat.com>
This commit is contained in:
Ben Thomasson
2026-04-28 10:47:22 -04:00
committed by GitHub
parent f3b7d442c3
commit d1b3ae53ae
11 changed files with 490 additions and 100 deletions

View File

@@ -174,8 +174,8 @@ SUMMARIZABLE_FK_FIELDS = {
'workflow_approval': DEFAULT_SUMMARY_FIELDS + ('timeout',),
'schedule': DEFAULT_SUMMARY_FIELDS + ('next_run',),
'unified_job_template': DEFAULT_SUMMARY_FIELDS + ('unified_job_type',),
'last_job': DEFAULT_SUMMARY_FIELDS + ('finished', 'status', 'failed', 'license_error', 'canceled_on'),
'last_job_host_summary': DEFAULT_SUMMARY_FIELDS + ('failed',),
# last_job and last_job_host_summary are derived from JobHostSummary in HostSerializer,
# not from the stale FK fields on Host.
'last_update': DEFAULT_SUMMARY_FIELDS + ('status', 'failed', 'license_error'),
'current_update': DEFAULT_SUMMARY_FIELDS + ('status', 'failed', 'license_error'),
'current_job': DEFAULT_SUMMARY_FIELDS + ('status', 'failed', 'license_error'),
@@ -1837,19 +1837,35 @@ class HostSerializer(BaseSerializerWithVariables):
res['ansible_facts'] = self.reverse('api:host_ansible_facts_detail', kwargs={'pk': obj.instance_id})
if obj.inventory:
res['inventory'] = self.reverse('api:inventory_detail', kwargs={'pk': obj.inventory.pk})
if obj.last_job:
res['last_job'] = self.reverse('api:job_detail', kwargs={'pk': obj.last_job.pk})
if obj.last_job_host_summary:
res['last_job_host_summary'] = self.reverse('api:job_host_summary_detail', kwargs={'pk': obj.last_job_host_summary.pk})
last_summary = obj.latest_summary
if last_summary:
res['last_job_host_summary'] = self.reverse('api:job_host_summary_detail', kwargs={'pk': last_summary.pk})
if last_summary.job_id:
res['last_job'] = self.reverse('api:job_detail', kwargs={'pk': last_summary.job_id})
return res
def get_summary_fields(self, obj):
d = super(HostSerializer, self).get_summary_fields(obj)
try:
d['last_job']['job_template_id'] = obj.last_job.job_template.id
d['last_job']['job_template_name'] = obj.last_job.job_template.name
except (KeyError, AttributeError):
pass
last_summary = obj.latest_summary
if last_summary:
d['last_job_host_summary'] = OrderedDict()
d['last_job_host_summary']['id'] = last_summary.id
d['last_job_host_summary']['failed'] = last_summary.failed
try:
last_job = last_summary.job
d['last_job'] = OrderedDict()
for field in DEFAULT_SUMMARY_FIELDS + ('finished', 'status', 'failed', 'canceled_on'):
fval = getattr(last_job, field, None)
if fval is not None:
d['last_job'][field] = fval
if last_job.job_template:
d['last_job']['job_template_id'] = last_job.job_template.id
d['last_job']['job_template_name'] = last_job.job_template.name
except ObjectDoesNotExist:
pass
else:
d.pop('last_job', None)
d.pop('last_job_host_summary', None)
if has_model_field_prefetched(obj, 'groups'):
group_list = sorted([{'id': g.id, 'name': g.name} for g in obj.groups.all()], key=lambda x: x['id'])[:5]
else:
@@ -1924,14 +1940,16 @@ class HostSerializer(BaseSerializerWithVariables):
return ret
if 'inventory' in ret and not obj.inventory:
ret['inventory'] = None
if 'last_job' in ret and not obj.last_job:
ret['last_job'] = None
if 'last_job_host_summary' in ret and not obj.last_job_host_summary:
ret['last_job_host_summary'] = None
last_summary = obj.latest_summary
if 'last_job' in ret:
ret['last_job'] = last_summary.job_id if last_summary else None
if 'last_job_host_summary' in ret:
ret['last_job_host_summary'] = last_summary.pk if last_summary else None
return ret
def get_has_active_failures(self, obj):
return bool(obj.last_job_host_summary and obj.last_job_host_summary.failed)
last_summary = obj.latest_summary
return bool(last_summary and last_summary.failed)
def get_has_inventory_sources(self, obj):
return obj.inventory_sources.exists()