fix(planner): keep control APIs responsive during Prometheus collection

[xianlubird]

Overview

Slow Prometheus requests currently run synchronously inside the Planner's async traffic collectors, blocking the event loop and delaying control API requests until collection finishes.

Summary

Run full traffic, KV-only, and standalone accept-length collection in a background thread. Publish shared metrics on the event loop only after successful collection, and keep control API requests responsive while Prometheus is slow.

Details

• Capture deployment state once per query context, deriving the model and decode labels from that state while preserving model-name fallback behavior.
• Serialize all three query scopes through the same cancellation-safe pipeline. A cancelled caller cannot publish late results, and the next query waits for its abandoned worker before reusing the Prometheus session.
• Make collect_accept_length() async across provider/environment protocols, forwarding, and the Noop implementation. Callers must now await it; standalone collection queries only accept length and does not publish shared metrics.
• Add regression coverage for HTTP responsiveness, context snapshots, cancellation, serialization, failure recovery, and idle normalization.
• Keep HTTP test imports at module scope and register aiohttp.test_utils in the marker-report dependency stubs so all tests remain collectable.

Where should the reviewer start?

Start with _collect_metrics() and _query_context() in components/src/dynamo/planner/environment/metrics_provider/prometheus_traffic_provider.py, then the regression tests in components/src/dynamo/planner/tests/unit/test_prometheus_traffic_provider.py.

Validation

• All pre-commit hooks applicable to the six changed files passed, including formatting, lint, and marker reporting. git diff --check passed.
• Marker-report collection found all 18 provider tests with no missing marker sets.
• All 18 provider tests passed locally in an isolated Python 3.12 run with real asyncio worker threads and local aiohttp HTTP sockets. The temporary runner preloaded dynamo.planner.core as a package with its real source path, bypassing only its __init__.py eager import of the unrelated AIC performance model. Provider, metrics, and HTTP code were not stubbed by the runner.
• Standard pytest collection remains blocked locally by missing aiconfigurator_core; the pinned AISimulate download did not finish. Full dependency-environment validation remains for CI.

Related Issues

• Confirmed — no related issue

Summary by CodeRabbit

• Bug Fixes
  • Improved Prometheus traffic collection reliability during concurrent requests and caller cancellation.
  • Prevented partial or overlapping metric updates.
  • Preserved existing metrics when queries fail and enabled successful retries.
  • Kept control API responses responsive while metric collection is in progress.
  • Improved normalization of idle metrics without affecting load measurements.

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[dynamo-ops]

/ok to test 407fe6c

[dynamo-ops]

/ok to test 3ec483b

[coderabbitai]

Walkthrough

Changes

Prometheus collection concurrency

Layer / File(s)	Summary
Query context and provider state components/src/dynamo/planner/environment/metrics_provider/prometheus_traffic_provider.py	The provider captures query parameters in immutable _QueryContext data and routes traffic observations through shared collected metrics.
Serialized background collection components/src/dynamo/planner/environment/metrics_provider/prometheus_traffic_provider.py	Full and KV-only Prometheus queries run through a serialized worker-thread pipeline that preserves in-flight work during caller cancellation and handles query failures.
Concurrency and regression coverage components/src/dynamo/planner/tests/unit/test_prometheus_traffic_provider.py	Tests cover control API responsiveness, cancellation, non-overlapping queries, retries, failure recovery, and idle metric normalization.

Estimated code review effort: 4 (Complex) | ~45 minutes

Merge Risk: 🟡 Moderate · up to 3ec48

The background collection change can query incorrect Prometheus labels during deployment transitions, and direct accept-length requests may contend with active collection on the shared client. Resolve both concurrency and snapshot-consistency issues before merge to avoid incorrect planner metrics or unreliable Prometheus requests.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 17 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly identifies the primary change: keeping Planner control APIs responsive during Prometheus collection.
Description check	✅ Passed	The description includes the required overview, details, reviewer starting point, and related-issues confirmation. It also provides useful validation information and accurately describes the implement…

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✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
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[coderabbitai]

Actionable comments posted: 4

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Inline comments:
In
`@components/src/dynamo/planner/environment/metrics_provider/prometheus_traffic_provider.py`:
- Around line 138-142: Update the relevant flow around _model_name and
_QueryContext to fetch deployment_state() once, then derive both model_name and
decode_info from that captured state so they always come from the same snapshot;
adjust _model_name or its caller as needed to reuse it. Add a regression test
using two distinct consecutive deployment-state snapshots that verifies the
query uses the model and decode endpoint from the single captured snapshot.
- Line 192: Update the direct accept-length query path around
_query_accept_length and collect_accept_length to acquire the same
_collection_lock used by _collect_metrics before accessing
prometheus_traffic_client. Ensure the lock is released after the synchronous
query, preserving the existing query result behavior and preventing overlap with
metric collection.

In
`@components/src/dynamo/planner/tests/unit/test_prometheus_traffic_provider.py`:
- Line 187: Move the aiohttp.test_utils import from the test body to module
scope, alongside the other imports. If the dependency may be unavailable, apply
a module-level pytest collection skip while preserving the existing test
behavior.
- Line 162: Update the fixture unpacking in the relevant test to bind the unused
provider value to `_` instead of `provider`, while preserving the client value
used by the test and resolving Ruff RUF059.

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ℹ️ Review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 7ee72a3 and 3ec483b.

📒 Files selected for processing (2)

• components/src/dynamo/planner/environment/metrics_provider/prometheus_traffic_provider.py
• components/src/dynamo/planner/tests/unit/test_prometheus_traffic_provider.py

Included review availability: Your plan provides up to 12 included reviews per hour; 11 remain after this review.

[dynamo-ops]

/ok to test 4daeebb

[dynamo-ops]

/ok to test 1b66df8

[tedzhouhk]

Reviewed cancellation handling, shared-client serialization, and predictor integration. All 64 related provider, control API, environment, and observer tests passed, along with 55 predictor, warmup, and throughput-scaling tests. Also verified responsiveness and cancellation serialization using the real Requests/Prometheus client against a local HTTP server and real Planner GET/PATCH handlers. No blocking code findings.

[tedzhouhk]

/ok to test 1b66df8

[dynamo-ops]

/ok to test a71e520

[xianlubird]

Quick update on the CI failure for a71e520c72: the Planner image build itself succeeded. The job failed afterward in Extract /compliance/ (NOTICES + CSV + CycloneDX), when BuildKit tried to read the amd64 metadata for ghcr.io/astral-sh/uv:0.12.0:

failed to authorize: Unavailable: error reading from server: EOF

Failed job and logs

This failure is unrelated to the Planner code changes in this PR

[dynamo-ops]

/ok to test f0a1d04

[dynamo-ops]

/ok to test 0dd19d5

[xianlubird]

The current dynamo-runtime / test / parallel cuda13.0, amd64 failure is unrelated to this PR's code changes. All tests in that job passed (702 passed, 16 skipped, exit code 0). The job turned red afterward when Upload Allure Results failed to finalize the artifact with 403 Forbidden: Error from intermediary.

Failure log. The dynamo-status-check failure is a consequence of that failed job. Both amd64 and arm64 Planner CPU tests also passed.

This is an artifact-upload infrastructure failure

[tedzhouhk]

/ok to test 9ce7d4b

[dynamo-ops]

/ok to test 9ce7d4b